I've tried to install MacPorts on Snow Leopard yesterday and it is not available.

Snow Leopard adoption will be slow.

Yes, it's faster and yes, it's stable, but Leopard is very faster and very stable too.

I've already pre-ordered my SL copy, but i'm thinking that i'm not going to install it any soon.

I installed MacPorts from SVN for Snow Leopard, I haven't had any problems yet.

Edit: I believe this is where I learned that installing from svn was necessary:

http://forums.macrumors.com/showthread.php?t=720035

This is one of the reasons I do all my development in a Linux VMWare image. No wrestling with MacPorts and I get to develop in an environment that much more closely mimics production. (easy snapshot/rollbacks of the whole OS are just a bonus)