When search giant Google announced on April 1 it was road-testing a new Web-based e-mail service, a lot of tech types assumed it was an April Fool's prank: One gigabyte of storage memory per account, for free? Yahoo charges $10 a year for a tenth of that space. Yet Gmail is for real. It sorts, searches and spam-filters your e-mail. Just two catches: it won't be widely available for up to six months (test accounts are being offered only to employees' friends and families right now). Also, every message is sponsored, often based on your text. If the e-mail server spots, say, the word camera in your message, it will append tiny text ads for electronics stores. Google promises that doesn't mean anyone human will be reading your e-mail, but privacy hawks may wish the whole thing had been a joke after all.