The search world was busy last week plotting elaborate April Fool's Day pranks, mostly taking the form of bogus new-product announcements. There were at least 28 Google-related hoaxes, some perpetrated from within the Googleplex itself, including "Gmail Custom Time," a tool that lets emailers predate emails in order never to miss a deadline again. The feature "utilizes an e-flux capacitor to resolve issues of causality," Google explained on the Gmail site. View it here: target="_blank">http://mail.google.com/mail/help/customtime/index.html. But the most elaborate prank may have been Google's announcement of Project Virgle, its joint venture with Virgin Group's Sir Richard Branson to establish a permanent human settlement on Mars. The prank included a several-Web-pages-deep outline (www.google.com/ virgle/index.html) of the Mars settlement, with maps and a 100-year plan. Richard Branson created a YouTube video (,a href="http://www.youtube.com/ watch?v=gWCQYcPlUng" target="_blank">www.youtube.com/ watch?v=gWCQYcPlUng) announcing the Mars project and even appeared on "The Late Late Show With Craig Ferguson" to announce the plan, straightfaced, never tipping the joke. Ferguson played along. Google founders Sergey Brin and Larry Page also created a 58-second YouTube video (www.youtube.com/ watch?v=PmSdy_9blB4) announcing the project. "This is the biggest endeavor we've ever undertaken at Google and at Virgin," Brin said in the video. "We're going to select the very first settlers of the planet Mars," Page said.