Twitter said by the end of the year we would start to see the first of the Pro business services, as 2009 draws to a close they are keeping their word with the announcement of "Contributors" for those businesses with multiple staff all responsible for using one account selected businesses will be able to include the tweeters name in the tweet.

(Image from Mashable)

So if Steve and John are both using @Myorg at the same time you can see which person tweeted what, great for customer service and creating tweet ownership.

For now this is only in testing and theirs no word when everyone will have access to this feature, at the moment it's likely any "business" features will be paid for extras separate from the normal Twitter experience.