has anyone played the US version online??

 I absolutely cannot stand brawl online......which is broken beyond repair and Nintendo refuses to fix it.

I am really hoping that mario kart wii does not lag online

If it's anything like in Europe, it will work great even when playing people from other continents. I've played many Japanese and Australians and the experience was great at least 99% of the time (yeah, I pulled the number out of my ass). It was also great when I played a few Americans today.

Here's hoping that Nintendo's servers are prepared to handle the increase in traffic due to the American launch.

Yes I've played the US version online for many hours. It works perfectly. Finding many online players is no problem. No lag whatsoever. You really cant even tell you are online.

EDIT:  I played it before most people got the game in the USA.  So today may be a little bit laggy.  But like any online game, just wait a few days.

I'm hoping I can get my hands on a copy. IN some case for SSBB, it did kinda lag, but not too much and most of the time, itwas like playing offline.
I sure hope that MKWii is the same.