The Daring Fireball Linked List has two posts on how buyers of the new Intel-based Mac minis may be getting something less than they were with the PowerPC-based versions:
Footnote 4 on the new Mac Mini tech specs features page:
Memory available to Mac OS X may vary depending on graphics needs. Minimum graphics memory usage is 80MB, resulting in 432MB of system memory available.
These machines are using very different — and decidedly inferior — graphic cards than the MacBook Pros and iMacs. Instead of a separate pool of video RAM, the video card uses regular RAM. 512 MB was barely tolerable on the old Minis — it's probably not even close to enough memory on the new ones. I figure if the minimum graphics memory usage is 80 MB, then it'll probably use at least 128 MB in real-world use, leaving only 384 MB for the system and applications.
From the Internet Archive's Wayback Machine cache of Apple's Mac Mini Graphics page from March 5, 2005:
Go ahead, just try to play Halo on a budget PC. Most say they're good for 2D games only. That's because an "integrated Intel graphics" chip steals power from the CPU and siphons off memory from system-level RAM. You'd have to buy an extra card to get the graphics performance of Mac mini, and some cheaper PCs don't even have an open slot to let you add one.
What a difference a year makes: the new Minis use an "integrated Intel graphics" chip that siphons memory from system-level RAM and doesn't have a slot for another video card.
Obviously you'll have to see them in the real world, but it does put the claims at launch of being between 2.5x-5x faster into a different light.