USA Nationals is about two weeks before the Worlds, which is the set-up for which teams go to the Beijing Olympics. Is it too close?? Marta thinks it's good:

It can get really tiring to have back-to-back competitions, but 2 weeks space in between should be good enough. 3 weeks would have been better though - most countries already have done their nationals it looks like from the news, and naming their Worlds team. Last year before the Worlds there was talk that the camp training might have been too much, contributing to over-use injuries. Maybe this time they will take that into account more. For club gymnastics, the day before commpetition usually you just do a run-through your routines. More practice though if you need it.

Actually, it might be 3 weeks between the actual competitions (depending on the scheduling for each category), but they do go to Germany earlier before the competition.