Randy Stewart While speaking last night at the Web 2.0 conference, Union Square Ventures partner Fred Wilson made an arresting claim: Google hasn't had any major innovations since Gmail, which rolled out six years ago. "They haven't home built from the ground up anything interesting in a half decade," he said.

He acknowledged that the company has done a great job with acquisitions. DoubleClick helped jumpstart its display advertising business, YouTube gave it a new source of indexable content in video, Writely gave it the beginnings of an enterprise productivity suite, and Android has been a big win in mobile. But as far as new products built in house? Nothing.

Wilson shared the stage with Kleiner Perkins partner John Doerr, who argued back that there's little effective difference between hiring individuals to build a product and hiring an entire team through an acquisition.

Wilson then criticized Facebook for its lack of innovation, at which point Doerr shot back with what I think was the most important statement of the conversation: "Ideas are easy. What's really dear is execution. Google executes. Facebook executes."

(You can watch the entire video of the conversation at Wilson's site. The conversation gets heated on this topic around 26:00.)

This struck home because I've argued for years that Microsoft's biggest problem isn't lack of innovation. The company has tons of interesting innovations kicking around in its research labs. Its problem has been turning those ideas into well-executed products that are released and updated on a timely schedule. Microsoft has also had a horrific record trying to integrate acquisitions, like the $6 billion purchase of online ad platform aQuantive, which went absolutely nowhere, or the $2 billion it spent on accounting software companies Great Plains and Navision, which have shown little growth since then.

The real problem for Google comes if it loses its ability to execute. With recent debacles like Wave and Buzz it's reasonable to question if this is already starting to happen. Its acquisition strategy is starting to look kind of haphazard as well. Google used visual search Like.com to build a fashion search vertical? Reminds me of Microsoft's acquisitions back in the 1990s.