They're here--sort of. Twitter has launched the early beta phase of its "verified accounts" program, a background-check for celebrities and other prominent users of the service to weed out impersonators and fake accounts. If they pass the test, they get a graphic "badge" much like a PayPal verified account's.
"We're starting with well-known accounts that have had problems with impersonation or identity confusion," an explanation from Twitter read. "We may verify more accounts in the future, but because of the cost and time required, we're only testing this feature with a small set of folks for the time being. As the test progresses we may be able to expand this test to more accounts over the next several months."
Twitter's team is rolling this out a bit prematurely because there are some powerful people breathing down their necks: the manager of the St. Louis Cardinals has filed a lawsuit against the service after someone started using it to impersonate him. There have also been embarrassing snafus involving a fake Dalai Lama account and a prankster who impersonated the Austin, Texas police department. By rolling out even a very bare-bones verification program, Twitter at least looks like it's doing something about the problem.
Right now, Twitter's verified accounts are mostly well-known ones (like @mashable), which suggests that the verification process thus far hasn't been particularly high-maintenance.
Here is the curious part: Twitter is currently only offering this service to individuals, not businesses. That raises the question of whether account verification will eventually be part of a paid "Twitter for business" account service that's rumored to be in the works. The presence of lawsuits, however, may have derailed plans to charge for account verification.
Either way, I suppose, you could get caught up in the debate over individuals who are businesses (Robert Scoble, anyone?), but that's a blog post for another day.