Seam 3 will have full support. Maybe in the end of the year you will have some beta version to try (just speculation).

Ops sorry, I forgot the last question. Glassfish prelude have the features of JEE6, is that right? Well maybe it have some complications cause it's too new, but you can give a try. In the Seam downloaded package there are some samples with Glassfish v2, maybe it's the same thing to configure, maybe not... try it. But remember that seam is not attached to any specific application server, I use it with a plain servlet container like Tomcat for example.

I have already created a couple of simple applications with jsf2, ICEfaces2 and Seam3, although this was prior to the latest changes with webbeans and Seam3 so I will revisit that shortly.  Glassfishv3 is the target AS for jee6 but Dan has put a lot of effort into making deployment to Glassfish easier with Seam2.2, so I'm sure you can expect the same attention to this in future.  (The api was still changing with Glassfishv3 last month)