Everyone, keep in mind that there are many possibilities for the 'rumored' MacMini update:
1) Apple is a premium seller so it's no reason to see them charge $599 for a base model. They are a hardware company at heart, and they do take pride in their work while giving people the service they expect for their money. The MacBook started off at $1099 before Apple decided to lower it to $999 for the polycarbonate model.
2) Because Apple has now chosen to go with NVIDIA for the chipset and display GPU, they have given MacBook onwers more bang for their money (5x gaming performance and improved rendering when using Cover Flow and using Final Cut Express. I bet people can now run the Adobe Production Suite or Final Cut Studio without any problems). Recall that in the video about the unibody MacBook, the engineer claimed that NVIDIA approached them about putting the 9400M in the desktop but they were interested in putting it into a laptop. they just might make their way to the minis.
3) With OpenCL specs already finalized and AMD/ATI announcing support for them + NVIDIA claims that the 9400M is fully compatible with it, it'll be nice to see who provides the display GPU for the MacMini.
4) Computing power has gotten faster and efficient while also becoming cheaper. It would be no surprise to see a 2.2Ghz Core 2 Duo as a minimum. In addition, the MacBook range now uses DD3 RAM, so they might make their way to the iMacs and minis. It's their chance to push it out to the market for acceptance since it takes less power to run it.
5) For the GPU, they could do some compromises by having a sizeable chunk as dedicated VRAM and the rest being shared from physical memory . For the 9400M, a dedicated 128MB and the remaining shared from memory would give it the 256MB, but there might even be a bid from AMD to replace it with their Radeon chipset. This will give owners more value.
6) Regarding ports and expansion, the minis feature 4 USB 2.0 ports so I guess they would want to keep it that way. Also, a miniDisplay port bundled with a adapter will help gain acceptance from the consumer. FW400 may not be eliminated as it's a standard on their desktop range. Gigabit Ethernet is a given, along with Airport wireless+Bluetooth2.1.
7) An entire aluminum enclosure that would be easily opened for future expandability can be a possibility. Not only lighter but also much sleeker in its visual aesthetics. Combine it with less power intensive componenets that also have less heat dissipation, and you're looking at a possible new HTPC. They might even be able to make it slightly thinner and smaller.
Overall, there are som many things to speculate about the mini but Apple hasn't forgotten how the mini helped push the Mac into households.
