It's a testament to the brilliance of the original Mac mini design that, as far as any consumer is likely to notice, it has barely changed since its inception. A look around the rear of this system reveals a notably changed port arrangement than on preceding models, but it is the internals that have seen the biggest update - in fact, it's only the internals that are different this iteration.
Whereas the most recent refresh before this brought the Mac mini up to date, hardware wise, with its peers, the current changes are 'just' spec bumps. Importantly, though, although there's no fundamental changes in the hardware on offer, the base specs at both the £499 and £649 price points have been raised. The cheaper Mac now gets a 2.26GHz Core 2 Duo CPU, 2GB of RAM and a 160GB hard drive as standard, while the £649 mini I have on my desk comes with a 2.53GHz processor, 4GB of RAM and a 320GB hard drive.
A 2.66GHz CPU upgrade is available for £120, but you'd be mad certifiably insane to spend an extra 18 per cent on the cost of the system for a five per cent speed boost. The £70 to upgrade the hard drive from 320GB to 500GB is on the dear side, too, but then when has Apple ever offered cheap upgrades? Some solace can be taken in the provision of £70-odd iLife '09 which takes care of most of the functionality you might want out of the box, which isn't already built into OS X.
Strictly speaking, the latest update has ushered in a noteworthy change in the external hardware, but not for your average user. The Mac mini with Snow Leopard Server is, as the name suggests, a mini with an unlimited client license for Apple's Server software. The significant difference, however, is that the DVD drive is eschewed in favour of a second hard drive, with two 500GB drives offered at most. Considering your next best option for an OS X-based server is a £1,899 Mac Pro it's a nice addition to the product range for small businesses customers.
It's a safe move for Apple, too. No business that was seriously considering a Mac Pro is going to look at the Mac mini server and think: "yep, that will do the job instead." The cost of offering a slightly different version of the mini chassis is likely negligible, too, so for all intents and purposes I imagine the price difference between the top spec mini and the version with Snow Leopard Server is almost all profit in Apple's pocket - nice!