GreenBorder acquired

By running unknown code in such a "time-out" setting, where the content remains isolated from a local host and any trusted network it is connected to, GreenBorder claims to prevent malware programs from delivering their nefarious payloads.

Google may have also like that the software will work with FireFox, and that they offer a free consumer version - Google loves to giveaway products (witness Picasa & Urchin)