SEO Tip #37: Why is the @ character ignored in search queries?
Matt Cutts: Well, historically, that was a deliberate choice because we didn’t want to index an email address, at least I think it was a deliberate choice. You don’t want somebody scraping Google to find a bunch of email addresses. So it’s kind of nice not to index the @ sign. It depends.
I could imagine us over time starting to treat that differently but at least for the time being that hasn’t been a popular request that we’ve heard enough that we would probably put resources into it right now.