Blah blah blah enormously hyped, blah blah persistant multiplayer yadda yadda battletag and built in chat client, I'm not going to bother boring you with things you already know.
Instead, I'm just gonna put it out there:
If you're going to be playing Diablo 3, and would like to play or chat with Super Awesome Gaming.SE Regulars like the amazing Sterno, or the inimitable StrixVaria, or that LessPopMoreFizz jackass, a bunch of us are adding our BattleTags and other relevant information to This Easy To Use Internet Spreadsheet List Thing.
You should add yours. And then we can play Diablo 3 together. And I can try to sell you lots of SoJ's at above market prices. Because that's what Internet Friends Are For.