We released our first production ClickOnce application a couple days ago...of course it will remain a beta version until MS releases vs 2005. I was a little concerned that we weren't allowed to release production software yet, but I checked with our ISV Buddy, and he told us as long as our clients were aware that it is beta, we could go ahead with it.
So far, one client is using it on four computers. Everything seems to be working well. We done a lot of testing to make sure it runs on different configurations.
We've been using internal ClickOnce apps for a while now. The ease of deployment and the updating capabilities is awesome. People also seem to adapt new applications easier and sooner if they just have to click a link.