A truck for Microsoft's Bing search engine has been driving around Google's Mountain View campus, apparently taking pictures. A Googler shot a photo of the vehicle — and then his friends went to work on Microsoft in the comments.

Judging from the cut-out panels on the sides, the truck looked to be taking pictures, presumably to power Microsoft online maps. But that didn't stop people from speculating about more sinister motives underneath the picture, taken by Google engineer DeWitt Clinton and uploaded to the Google Buzz social network. Wrote one reader of DeWitt's Buzz, "Maybe its because Bing returns search results so slowly that they thought it would be a lot faster to drive them over to Google and have you guys process them." Another:"Its like the roach coach of search engines." And another, who works at e-commerce company Amazon: "Maybe they're bringing a shipment of fail?"

Of course, Microsoft's Silicon Valley campus is just 100 yards away from Google HQ, as Clinton pointed out. But that's probably not going to stop the jokes.