If you look at the about box for X-Plane 9 RC1, it still lists itself as a beta.
Here’s the thing: that label is dynamic. Right now when X-Plane calls up the server to see if there is a new patch, it notices that its current version (900Rc1) is newer than the latest “final version”. (This is because we haven’t declared any version of 9.xx final yet.)
So it thinks for a second and goes “oh – I’m newer than the latest final version, I must be a beta.” And that yellow beta label appears.
When we finally declare a version final (which involves tweaking the versions listed on the servers) the existing code will then look at the server and go “oh, I’m the latest version” and that beta label will disappear.