Looks really good. Great colors.
Things that could be better:
1. Each box on the left has a big blue border(gradient), that looks kinda awkward, it's empty every time, so just takes place.
2. The latest post on each forum looks like it was forced to fit there, and hasn't really got it's place.
2. The options (tools, search thread...) are really small, makes the look bad IMO ... and I'd make the quick reply button just larger in width.

Great layout, I really like it