[0004] Bandwidth limitations in the wireless communication channel(s) available to data broadcasting services establish a real physical limit to the amount of content that a data broadcasting service can distribute in a given time period. Improved content distribution schemes would enable data broadcasting services to manage limited bandwidth more effectively and to provide improved services to customers. SUMMARY [0005] Implementations described and claimed herein provide systems and methods for performing differential updates for data broadcasting. In exemplary implementations one or more computing devices associated with a data broadcasting system maintains profile data records for subscribers to the data broadcasting system. The allocation of content in the broadcast carousel for a broadcast region may be adjusted in response to version information for specific documents among subscribers in the broadcast region. BRIEF DESCRIPTION OF THE DRAWINGS [0006] Fig. 1 is a schematic illustration of an exemplary implementation of a data broadcasting network. [0007] Fig. 2 is a schematic depiction of an exemplary system for intelligent data broadcasting. [0008] Fig. 3 is an illustration of an exemplary data structure for holding subscriber profile information. [0009] Fig. 4 is an illustration of a data structure representing a data broadcasting carousel. [0010] Fig. 5 is a flowchart illustrating operations in an exemplary method for performing differential updates in data broadcasting. [0011] Fig. 6 is a schematic illustration of an exemplary computing device. DETAILED DESCRIPTION [0012] Exemplary implementations of methods, systems, and computer program products for intelligent data broadcasting are described herein. In certain implementations, techniques can utilize subscriber preference and/or location information to adjust the data broadcast content within a specific data broadcast region. In certain implementations, a network management system can adjust data broadcast content on one or more data broadcasting regions in a dynamic fashion in response to changes in the distribution of subscriber preferences in the region. Exemplary Operating Environment [0013] Fig. 1 is a schematic illustration of an exemplary implementation of a data broadcasting environment 100 in which the subject matter described herein may be implemented. It will be appreciated that the environment 100 depicted in Fig. 1 is merely an exemplary environment and is not intended to suggest any limitation as to particular uses or functionality. The subject matter described herein may be implemented in a wide variety of data distribution environments including, but not limited to, radio, television, and satellite networks, digital radio systems, broadcast disk systems, publish/subscribe systems, Internet-based broadcasting systems, and the like. [0014] Referring to Fig. 1, the environment 100 includes at least a head end 112 that broadcasts data throughout a broadcast region 110 to one or more subscriber units 114 that subscribe to a data broadcasting service transmitted from head end 112. As used herein, the term broadcast and its derivatives should be construed broadly to encompass any form of modulating, coding, and/or transmitting of a communication signal across a communication medium,, wired or wireless. Similarly, as used herein, the term "subscribe" should be construed broadly to encompass any form of receiving, demodulating, and/or decoding of data broadcast head end 112. [0015] In the implementation depicted in Fig. 1 the broadcast environment 100 includes a single broadcast region 110 which includes a head end 112, which broadcasts data throughout its broadcast region. Although Fig. 1 illustrates three a single head end 112 defining a single broadcast region 110, it will be appreciated that the specific number of regions is not important, and may vary depending upon, e.g., the geographic size of the operating environment, transmission power constraints, and interference and/or obstructions of the signal(s) broadcast from the head end 112. Also, it will be appreciated that there need not be a one-to-one correspondence between head ends and broadcast regions. [0016] Head end 112 further includes infrastructure necessary for broadcasting a data signal. In a wireless communication environment such infrastructure may include equipment for encoding, modulating, and transmitting or transceiving a radio frequency (RF) signal at a specific frequency (or frequencies), or in accordance with a specific multi-frequency protocol. Such equipment is readily commercially available, and is known to those skilled in the art. The particular encoding, modulating, and/or transmission scheme is not important. [0017] The broadcast environment 100 further includes a plurality of subscriber units 114, 116, 118, which may be embodied as wireless communication devices such as, e.g., personal computers (PCs), laptop computers, personal digital assistants (PDAs), mobile phones, or the like. [0018] In an exemplary implementation the head end 112 may be assigned a unique identifier within broadcast environment 100. A head end 112 may be identified by a network address, station name, a carrier frequency, or other distinct designation. A data broadcast from a head end 112 to a subscriber unit 114, 116, 118 takes place over a communication channel. In an exemplary implementation the communication channel(s) may be defined by modulating a carrier wave in accordance with any conventional RF broadcasting technique such as, e.g., TDMA, FDMA, CDMA, or the like. The transmitted content may include various forms of data including, e.g., text, audio, video, and may also include control signals including, e.g., timing signals, power signals, location signals, etc. Control signals may be broadcast in-band, or on a separate control channel. In alternate embodiments the communication channel may comprise an uplink channel that may be implemented over a wired network such as, e.g., the internet, or a wireless network, or combinations thereof. [0019] Broadcast environment 100 further includes a broadcast center 140 for managing the broadcast operations of head ends 112 and a management center 150 for managing subscriber profile information and other network management information. Broadcast center 140 includes a broadcast manager 142 and a broadcast data store 144. Management center 150 includes a subscriber profile manager 152 and a subscriber data profile 154. Broadly, the broadcast center 140 cooperates with the management center 150 to manage subscriber information, network information, and data broadcasting from one or more of the respective head ends 112 of the operating environment 100. [0020] In one exemplary implementation broadcast center 140 and management center 150 may reside on a single computing device such as, e.g., a server computer associated with broadcasting environment 100. In alternate implementations the responsibility for broadcast management and subscriber