Ah.... this speculation really brings back the memories of PowerPC rumors. Like when everyone was speculating if we see 3 Ghz G5's. I thought the feeling would be gone now we have intel (and its roadmaps), but debating on wether we might see a Core 2 Duo line-up soon brings the excitement right back. Hope this time the rumors do come true. This eventhough I am completely not in the market for a new Mac (neither was I for a 3 Ghz PowerMac

)
You got some
serious ideas frankie

Yeah I also had that idea. Given the number of people that use the mini as server or multimedia center that will be nice (Microsoft is already planning for giving mini-screen support in vista, so it is a good idea). I actually though about this to turn the mini into a laptop. Thus some kind of battery+Screen+keyboard add-on. This would truly emphasize the phrase BYOMKM (Bring your own Monitor Keyboard and mouse). But then again; a laptop would be much easier.
Yeah you are quite right. It is predominantly the size of 3.5" hard disk that will hardly even fit in the total casing.
The original G4 mini had a dedicated graphics chip and full size SDRAM so that is not the problem. Maybe the Mini should get an external SATA port on the bottom. External SATA ports are becoming available for PC's so it might be an idea for the mini. This way makers of external hard disks like LaCie can offer a real high performance solution. The hard disk is now a serious bottleneck in the mini's performance as can be seen
here (g4 mini benchmark) and a standard 3.5" disk would solve this. Particularly when loading applications and interface responsiveness (especially if you have not that much ram as how most people configure their mini which, to make things worse, also uses the ram as video memory).
Or just wait until Robson flash-harddisks will be included in Macs. This will make the performance better and eliminate the need for large and high data capacity hard disks. Since not many users will be able to fill a 250 GB harddisk, although they might want the performance of a 250 GB harddisk.