Ok, my predictions. I am also going to add the totals to my sig so I can brag in January. 
Basically, I feel the Wii will ramp up production and not be sold out (beginning in May) for the rest of the year. The 360 will remain constant and not really grow. Lastly, the PS3. I think it will do better than the 360 in Japan and Europe and only really grow in sales in Japan, not by much though. In fact I think it will sell best in the 'Others' category on average.
In August Wii and 360 will be neck-n-neck in worldwide sales and by the end of the year PS3 will almost have sold more units in 'Others' than 360, also, Wii will not outsell 360 in either NA or Others by end of year. HOWEVER, it will be very close in both territories. In fact if it weren't for the complete failure of 360 in Japan, it would have kept the lead THIS year.
January 1, 2008.
Wii = 19m
360 = 15m
PS3 = 11m
Due to this 8m+ lead for Wii over the PS3 and the complete failure in Japan for 360, it will dominate all from here on out. It will gain and keep a huge 3rd party dev support and have the most exclusives. This gives Wii the only item really needed to have the largest market share, the most games.
