With the rise of Twitter, and the heavy use of the “@” sign in Tweets, why doesn’t Google index this symbol to make it easier to find all references? For example a search for “mattcutts” and @mattcutts” delivers the same results.

According to Matt Cutts, Spam Czar @ Google, the reason was intentional. Email addresses. If Google did index the “@” sign, email addresses would come through and it would just invite all the scrapers to harvest even more email addresses for their Spam campaigns. Matt did state that this could change in the future.

For me, just use the Search function in Twitter and be done with it.

Source: Matt Cutts Video