When Careers first launched, I purchased a 3-year spot. Now that Careers 2.0 is launched, we're able to 'invite' others into Careers. I have a high Stack Overflow reputation and I bought into careers, so I'm assuming I have invites waiting for me to give out. Where and how do I give out those invites?
As jjnguy figured out, the whole thing was a bit rushed at the end because of the LAUNCH conference. Invites are working, but nobody has them yet while we iron out the other bugs (wouldn't want you to invite your friends to a buggy site!). We'll start rolling them out in the next few days.
Once you have invites, they will show up in the menu on the profile page, right above the messages link.
Invites are now being given out normally. If you don't have invites to give out yet, it may be because your profile is not complete enough.