From someone else
"This is an amazing service. When you get a beta code, you download the program and make an account. You get 2GB worth of space just to play around with - which is enough for me. This works with Windows XP/Vista and Mac. I have installed it on my Vista machine, my mac and my laptop which is running Windows XP."
Please leave rep if happy =]
Update : 6 august - none left, but if you ask people on the thread nicely enough they should have ten each.
Right spobby has now run out of invites, so the next ten people wanting one can now pm me.