Remember as with any tool in today's technology era, if handled improperly, it can be just noise. There are so many Twitterers out there, it's difficult to follow everybody! So choose wisely and you will be blessed with first hand knowledge from the "mouth of the horse" itself. So learning photography need not be done with classical methods like workshops and books, today there are other avenues like podcasts and crowd sourcing tools like Twitter which will bring more information than you will ever be able to learn. Remember, the sky is the limit! Oh, by the way, if you feel this article has helped you in getting more from social networking and would like to know more, why don't you follow me on Twitter. ;-)
Update: There is a new database like page which lists and refreshes regularly showing all the Photography folks on Twitter, the page can be accessed at Photocritic's Photographers on Twitter, although I have to warn you that there are too many entries in there and it mind be a little difficult to find people.A better solutiont is to find and follow people on the Twiiter directory pages called Wefollow. It has a listing of most influential Photographers on Twitter, which frankly makes ore sense to me.