Just got mine from Amazon and installed, though won't be able to play for another 3-ish hours. ;_;
Funny thing, I installed it and went to activate it and it said "The authentication key you entered cannot be claimed". I didn't know if my CD key had already been taken or what and started panicking. I entered it several times and nothing!
I noticed the first letter looked a little funny and thought that was it, I thought it had to be an A or an R and tried both with no luck. I searched around and apparently that letter I thought was an A or R was actually an H and a lot of people were having the same problem I did.
The g on Wings of Liberty covers up the first letter perfectly so it looks like an A or R, not-so-much an H. -_-