Thanks for the info!
To expand on this, for the past week I have been developing an eventual production application using Granite Data Services and Seam. Though the starter project doesn't look much like a seam-gen project (but it's workable), there are just a few steps you need to take to get everything working.
Here are some development notes I took down in process:
With the release of BlazeDS (an OSS offering of Flex Data Services), I don't know the future of GDS, but it works well for now.
Feel free to post questions/comments here or by email. I'm happy to see this marriage garner more support.