Twitter has announced the beta launch of the "verified accounts" functionality that it's been promising for some time, to deal with the issue of impersonation on the service.

Verified accounts will feature a special seal on them that mark them as genuine. Initially, it will only be available to "public officials, public agencies, famous artists, athletes, and other well known individuals at risk of impersonation".

The company has made the move after a lawsuit was launched by Tony La Russa, the manager of the St Louis Cardinals - a US baseball team. He's accusing the service of not doing enough to stop people pretending to be those that they're not.

Twitter's response? "Mr. La Russa’s lawsuit was an unnecessary waste of judicial resources bordering on frivolous". However, that hasn't stopped them wanting to deal with the problem.

The service will be invite-only to start with, and of course if you're wondering whether you're enough of a celebrity to be included, then you're not. It won't be available to businesses for now, but the company acknowledges that's an arena for future growth.

Whether or not the service will be charging for these verified accounts isn't mentioned, however many commenters have suggested that it could be a great way for the microblogging service to finally make some money.