I found this information on the Bejing olympics site,so I suppose it is the most up to date. Andy Roddick of course isn't listed, but since some of the figures vary from those on the ATP site it is very possible that his have also changed.
Federer 6'1" 176lbs.
Nadal 6'1" 176lbs.
Djokovic 6'3" 176lbs.
Murray 6'2" 183lbs
Blake 6'1" 183lbs
Nalbandian 5'11" 174lbs
176 is the magic number!!! It's the secret to top 3 tennis. Djokovic is even 176 despite being so tall.