There's no support in the remoting module yet, but it is planned. I don't know about the rest module, you'll need to check the reference docs.
Thank you for your feedback. I'm looking very much forward to Seam 3 and as part of it the remoting module.
I will check the rest doc.
My reason for asking: I have a customer who wants to decide for his strategic Java EE platform within the next month. His web platform however needs strong comet support. That's why I am asking for a roadmap. At the moment, concerning remoting with comet I could only advice him to use a framework module having comet support already included (such as DWR) or on the short-term roadmap.
So, if your customer is using JSF you shoud take a look at the ICEfaces Framework, especially at the ICEpush. It is a Comet function, small, fast and easy to use.