Almost all Web sign-ups these days require you to look at those scrambled letters in a box; you're all too familiar with it, and it happens to be called the CAPTCHA system. You might know why you're required to do this: it's so that people can't unleash bots -- that is, automated programs -- to sign up and clutter the system (a forum, for example, or a social networking site) with spam.
Google's having a problem now. Apparently, bots are getting past the CAPTCHA system in its sign-up process; spammers would love to have a lot of Gmail accounts, as you might expect. For one, since Google is so popular and free, other systems would have a tough time blacklisting Google accounts. Then there's the fact that there's a variety of services that Google offers, and a spammer with a Gmail account could also, for example, spam Blogger accounts.