Fifty thousand dollars will only go so far. As the winner of last year’s TechCrunch50, that’s how much workgroup micro-messaging service Yammer received in prize money. But Yammer has now raised a $5 million series A financing from the Founders Fund and Charles River Ventures, according to founder David Sacks. Yammer is a spinoff from genealogy site Geni, which also just received another $5 million from the same investors in a series C financing.

The Founders Fund is a $220 million seed fund whose partners are mostly former execs from PayPal, where Sacks himself was the COO.

The A round should help Yammer make more inroads into companies big and small. Yammer is an enterprise version of Twitter that helps people in companies keep up with what everyone else is doing. It works especially well with far-flung employees (we use it every day at TechCrunch). But many competitors have already sprung up, including Present.ly and WizeHive. And Twitter itself could easily move into the enterprise market simply by launching a groups feature, as it has done in Japan.