I feel incredibly stupid for even asking this since the answer might already be under my nose but here it goes:
TweetMeme has a Re-tweet twitter widget that publishers can place on their blogs. When a user clicks on the widget, it pops open a window which allows the user to authenticate themselves with twitter and then re-tweet.
This seems to use some special Twitter oauth popup form factor - unless there is something fancier happening under the surface to authenticate the user.
The pop-up window looks like this:
I'd rather handle an authentication via a pop-up rather than send the user to a brand new page (for the app I'm working on) and they seem to have the most graceful solution. Thoughts on how they did this?