You're absolutely right, Tim, version10 is the latest release, but many people here are adventurous and like to jump in and play with the beta versions.
Their feedback helps make the next version (in this case v11) of Media Center better. Those using the beta version tend to forget that it is beta, because it is quite stable, but there will still be quite a bit of tweaking before the final version of 11 is released later this year some time, (they're still working on the beer dispensing thing).
A discount has always been offered to those who want to upgrade to the next version, (or the beta).
This is the best forum around, there's a lot knowledge and experience here and folks are usually pretty quick to chime in. (and it's a lot better than getting one of those auto-generated emails from some cold support department).
I'm one of those doesn't get upgrade fever very often, I'm still running version9, and I don't play around with the "fields" so you'l have to wait for someone else to help you with the question.
And as Alex said, welcome to MC and enjoy!