This past weekend, I had the pleasure of purchasing a very slightly used 12" iBook G4, 1.33 Mhz, with 1.5GB Ram.
I have spent the past five years or so in the PC realm, and during that time became a heavy World of Warcraft player. As the iBooks have evolved I have been very interested in getting one - but have been hesitant about them because of their video memory size - and fear that the game wouldn't play well.
After having the computer for this whole week, and thoroughly playing the game during that time -- I can safely put my fears to rest.
World of Warcraft runs great of MY iBook. That is not to say that it will run great on every iBook -- I cannot say how it would run on a unit without the maximum RAM.
Now- bear in mind - I am not getting 50+ frames per second, as are possible with the new iMacs and the updated Intel binaries. I am also not getting 10 frames per second, as I was afraid I would see. What I am getting is consistent 26+ frames per second, which in my opinion is perfectly adequate to enjoy this game. Dungeons/instances get a bit more FPS, and large cities get a bit less. (I was getting low 20's for Ironforge)
Overall I was very surprised and pleased with the performance of WoW on this iBook. If you are someone who loves playing the game, as I do, and you've been holding off on buying an iBook - for fears that the game would not play -- do not be concerned. The game plays great. I would, however, recommend that you get as much RAM as possible - as I believe that does have a great impact on the game.