Prior to May 2006's Bensley platform launch, Intel's E7520 (Lindenhurst) platform held up their dual processor platform for more than 1.5 years. Albeit it stayed on longer than anticipated, the Bensley platform launch was closely tied with introduction of the Xeon 5000 series (Dempsey) processors to kick start the new era in proper order. The Intel 5000 series chipset (Blackford) of the Bensley platform had a lot going for it, including the fact that it's designed to support not only the then launched Intel Xeon 5000 processors, but also the following month's launch of the Intel Xeon 5100 processors (Woodcrest) and the soon to be announced quad-core Xeon 5300 processor (Clovertown). To make it even more palatable, all of these processors will use the same packaging and pin-out to ensure compatibility with the LGA771 socket and allow direct drop in upgrades along the way (as long as the board's BIOS is qualified to support them).
To be well prepared to feed current and upcoming processors' heavy compute intensive tasks, the Intel 5000 series chipset is also the first DP platform to feature dual independent buses (DIB) to the processors. Instead of the shared bus topology of past chipsets where switching occurred to serve each processor (and further switching occurred if it was a dual-core processor), the new Blackford chipset has given each processor a full speed FSB to communicate simultaneously and frequencies have been boosted from a paltry 800MHz to support up to 1333MHz. All these 'upgrades' give the Bensley platform a peak FSB bandwidth of 21GB/s versus just 6.4GB/s on the Lindenhurst. Thus even the average sustained FSB bandwidth is far more than the peak FSB bandwidth of the old E7520. While all this bandwidth is not really necessary for the current Xeon 5100 processor series, the upcoming quad-core versions would definitely find that handy.
You can make a good guess that Intel 5000 series chipsets are pretty huge and complex and indeed they are at 52 million transistors (130nm process technology) and 1432 'pin-outs'. One version, the 5000X (codenamed Greencreek), is targeted for workstations and incorporates a 16MB snoop filter whose goal is to boost the efficiency of the dual independents busses to the processors. Used as a form of cache state information storage, it also works hand-in-hand with the Coherency Engine that's in the backend of the chipset closely monitoring and orchestrating events ands transactions within the platform. Obviously, the Intel 5000X chipset is larger than its other peers cramming 65 million transistors and that's a higher transistor count than the early Pentium 4 processors could boast!