Now before you get too excited, there are quite a few limitations to these galleries. First off, they’re not permanent. They’ll display the 100 most recent photos you’ve uploaded in chronological order. They’ll show pictures that you’ve uploaded to Twitter directly as well as anything you’ve linked from yFrog, TwitPic and Instagram, but video thumbnails won’t show up.
The new gallery update hasn’t gotten around to everyone yet , but certain users are seeing it rolled out already. You’ll find the option to view a gallery – if it’s possible on your account – under your name and info. You’ll see your recent photos and then a “View All” option.