X360 will probably peak in 08 or 09. It has been picking up some real steam in Others lately, and I am relatively certain 09 will > 08 there. Not sure about Americas, but it will probably peak there in 08. Either way, 09 should be within 10% of 08.
Ps3 will probably peak in 09. It is its 3rd year, and it will see its most important price drop. Still, it looks like it has lost its momentum, and 09 probably won't be a lot bigger than 08 (ala max 15% difference really).
Wii will peak in 09. It is unlikely that Nintendo will up shipments (after all, you can't sell a lot more than 130M in the western world, that's selling to 2/3 homes, and with 30M as a max from Japan + rest of the world, 160M is really the ceiling (well, maybe 170M, but 160M is more realistic)). If Wii was to peak later than 09, it would just beat it by 1M max (which is less than 5%)
DS will have its peak year in 08. 09 should be 07 size (10% smaller than 08)
PsP will have its peak in 08 too.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS
