ExtremeTech reviews the two newest Shuttle offerings. Shuttle is now offering both P4- as well as AMD/NForce2-based systems, although as mentioned at the end of the article, choosing a P4 system means at least a $280US price differential.
You can think of the Shuttle XPC line as the Mini Cooper of the PC universe. Yes, there are other small form factor PCs out there, some even appearing to be near-clones of the XPC line, but none have achieved quite the cachet of Shuttle's cute aluminum cubes. While there have been other compact PC's in the past, Shuttle pioneered the idea of small form factor PCs with large PC performance.
I think it’s great that Shuttle is continuing to come out with these powerful little boxes – it means the less-powerful, slightly older barebones systems will continue to get cheaper.