I'm getting session expired as well. And my first reaction was "Fuck, I can't handle this many games at the same time." So I shut it down and loaded up HL2 a bit.
They will not let people into retail servers until the 23rd anyways, no worries bro.
Lots of people had fun trying to convince people open beta was already over in chat before I logged out, though. "Ooh, no, my life is over!" replies and all that. Are those the b.net kiddies?
I am definitely getting this when it launches in Europe next year. Even though I never played any char higher than 10 (beta/demo is for exploring breadth to decide on a race/class combo, e.g. undead warlock or nightelf rogue).