Third party game announcements for the Wii have outpaced announcements for the XBox 360 and PS3 since (roughly) E3 2006; the reason for that is developers saw the excitement anound the Wii at E3 and found resources to develop or port games to the Wii. Most of these games are discounted as third party support because they were not particularly good ...
One thing people often forget is that even on the PS2, PSP, Nintendo DS, Gamecube, XBox and Wii it takes (at least) 12 to 18 months to develop a good game from scratch and unlike the PS3 developers were not anticipating the Wii being super successfull in late 2005/early 2006. Starting in early 2008 you will really start to see a major improvement in the quantity and quality of game announcements for the Wii.
