I started to look at Vala some months ago, and compiled a few test programs. Since then there's been progress, the language has evolved and there are more bindings. What looks really nice is that there's a Hildon binding (the OS2008 kind, not the OS2007 kind, which is why I haven't written anything yet that'll execute on my N800), and what's more - Debian (for the desktop) now includes full Hildon, so the application I started on a while ago compiles and run on my Debian computer - hildonized and all. When the time comes it should be just a recompile to make it run on my N800 (when I get around to switch to OS2008).

As for IDEs, I don't personally care much for those, I just need an Emacs binding. For now C-mode works close enough, but I'm sure someone has a Vala binding somewhere.