Just to clarify things (because i got my beta access today!!! :):):D:D:thumbsup: )
You don't actually get a key to access starcraft, you gotta have a battle.net account and your account gets selected for beta access. So you cant really give your key to someone else, unless you actually give away your whole battle.net account.
Don't rely on waiting for the beta to arrive via email. I found out that I got into the beta (and started playing) by logging on to my bnet account, and this was 3-4 days before the email notification arrived.