Even before Twitter purchased Summize and turned it into Twitter Search, users started to realize that a deleted tweet was never truly deleted. If you knew what it said, you could easily find it by searching for some of the words, and even if you didn't, you could see someone's deleted tweets in the results for "from:username." M.G. Siegler over at TechCrunch noticed that after Twitter made high-profile search deals with Google and Microsoft, they also decided to clean up the problem and stop indexing deleted tweets.

This is a big win for personal privacy, because although Twitter Search is relatively low-volume and you'd have to know where to look to find a deleted tweet, the sheer number of Google searches that happen every day would inevitably result in people seeing tweets they weren't meant to. I think it's great that Twitter has closed this privacy loophole, but it's also important to think before you post anything, because with retweets, third-party aggregators and the like, your tweets aren't always going to be isolated to your Twitter page. Treating them as public, Google-indexable info is probably the best policy.