The launch of Twitter's "verified accounts" functionality was promised to us earlier in the week, and here it is. Various celebrities including Oprah Winfrey, MC Hammer and Ashton Kutcher have now got "verified" badges next to their names.

However so far it appears to be US-only. UK Twitter stars like Stephen Fry and Jonathan Ross don't have the badge. Some obvious candidates in the States are missing it too, like Britney Spears.

The Twitter team cautions us not to assume they're fakes: "Please note that this doesn't mean accounts without a verification seal are fake—the vast majority of Twitter accounts are not impersonators".

As previously reported, the verified accounts are currently invite-only. They're not available for business yet, either. Many have speculated that charging for a verified account could go some way towards a genuine business model for the microblogging service.