The answer is quite simple. Log into your account, and right-click (or control-click) on the "My Profile" link. Then select "Copy link" from the contextual menu and you're all set! Paste that address in Twitter, email or where ever you want to broadcast your shiny new account.
Another, more roundabout way of accomplishing the same task is to search for yourself on Ping, and when your name shows up under "People," right-click your avatar icon and choose "Copy link."
We'll have more iTunes 10 tips and tricks coming right up.