Damnit, wasn't first
Got my invite today as well, as said I used a proxy to signup, seems there's no need for a proxy once you get the invite which is nice,
Downloading the Music Manager now and it's taking a while...
EDIT:
Update, just remembered I selected the option to get some free songs (did the select all so a lot of junk I don't really want but hey

) so I went and got the Music app that supports the beta, unfortunately the market won't let me install it but who needs the market when you've got the community:
http://www.multiupload.com/KIM5LQDL0K
Installed that, works fine on my SGS2, no idea if it's the latest but it'll do until they let me install it properly, I'm currently playing a SOTD free song from the cloud, how awesome is that
I'm using Wifi but after pressing play you can see the the buffering bar go across much like youtube and on wifi it takes a just seconds to get all the way across, I'll probably test on 3G/H at lunch and then on GPRS for a laugh when I get home this afternoon.