If you notice on the redesigned PS3 there are indents surrounded the disc tray. Perhaps in the original there are similar things but not visible? I'm not sure. Haven't seen a disc put in it.
As for the disc size for the Wii. It amazes me just seeing a disc pop out of it. So small.
http://youtube.com/watch?v=QYNZ90kB2...ch=wii%20eject
Incase anyone cares here's the volume:
PlayStation 3 8726.9 cm^3
Xbox 7727.4 cm^3
Xbox 360 6616.9 cm^3
PlayStation 2 4179.1 cm^3
Gamecube 2656.5 cm^3
PStwo 978.9 cm^3
Wii 955.5 cm^3