It has been discussed a thousand times here already

The most common theory is : no G4 in an iBook before a G5 PowerBoook is released. Or maybe there will never be a G4 iBook since a new G3 is underway. The new version has the ability to use a 200 mhz bus (the current version too but Apple sticks to 100 mhz ...) and a bigger L2 cache. The next G3 could be much more powerful than the current one. The chip will be produced by IBM from next December and could be announced in new iBooks maybe at the next Macworld in January. Of course in the meantime Apple will update the iBook line with a giant 100 Mhz jump as usual and maybe a better video chip.

Nothing else should change. I don't see them adding airport extreme, DDRAM and a 133 mhz bus now, before using the new chip early next year.
By the way, all brand new iBook models (the first ones and the icebook change) have always been introduced in spring ...
