As Twitter's current developer Terms of Service prohibit third-party apps from using the company's name, this suggests the app is something developed in-house.
The discovery was made by Jonathan Gottfriend. He was monitoring the hashtag #throughglass -- Google has attached the hashtag “#throughglass” to Google+ posts made using Google Glass hardware -- and noticed that some of them had the tagline "Twitter for Glass."
Although the original poster's account -- @MogroothMuddler -- has since been deleted, that handle alone is a clue. The handle “@Mogrooth” belongs to Shiv Ramamurthi, who is a mobile engineering manager at Twitter. Not enough proof? He the handle “Mogrooth” across multiple accounts, including his LinkedIn profile and other currently active Twitter test accounts.
In addition, the Twitter accounts of Googlers Sidney Chang, Yury Pinsky, Sophia Yang and Steve Lee, which were pointed out by Gottfried, all seemed to be posting images with a "Twitter for Glass" tagline. Notably, though, looking at those images today, they appear to have that tagline removed.
The question, then, is not if, but when will a Twitter Glass app be released?