Germany will apparently have the luxury of two video game trade-shows in 2009. After another visitor record for the GC 2008 in Leipzig the Leipzig trade-show wants to continue next year despite the decision of the video game trade organization BIU to move to Cologne.
203,000 visitors have been at the GC 2008, which is 18,000 more than at the GC 2007.
It would be very strange to have two video game trade-shows within weeks. The GC 2009 would take place in August again and the GAMESCom in Cologne is slated for September.

I guess the video game companies will have to decide which show to attend. They will be making or breaking a show. Nintendo's absence at the GC 2008 apparently didn't hurt.
More details on Heise (German).