When I say 3 CDs, I'm not talking about the Developer Tools. There is a Mac OS X Install CD 1, 2, and 3, the last one only being 90 MB or so.
I realize that Mac OS X is a new thing (I'm not new to the Mac anyway), it is just exciting at how much systems in general have evolved over time, space needed, installation media, etc.
On a different note, the Installer for Mac OS X has gotten some changes:
1) Panther-esque 'X" background
2) The Side Panel (left side, showing the steps) font now looks different (Myriad prehaps, or Gill Sans)
3) Installer tells what discs are needed right off the bat
4) Customization panel UI has been changed some
Also, a lot of bugs have been fixed, and some minor, but noticable UI tweaks have been done (I've seen it in System Prefs: the rows in "View All" alternate (light gray, dark gray, etc.; the lock button now animates and is in color; some prefPanes more refined, like the Accounts Limitations tab actually having content now.)