While he doesn't guarantee results, since the cluster can check the WPA-PSK password against 135 million possible passwords in the 20-minutes your money gets you, I'd say the odds are darn good that they'll break that network's password.
In a PC World interview, Marlinspike explained that he created the site to speed up WPA network auditing because "It's kind of a drag if it takes five days or two weeks to get your results." And, of course, only a dedicated attacker would bother to take that long.
OK. So, yes, you could use WPA Cracker for testing security, and, as in the same PC World story points out, it's an easy way to point out to management just how easy it can be to beat WPA-PSK these days. That said, it's also an easy way to break into someone's network.
This bothers me. Yes, a bigger company can simply move up to a more secure Wi-Fi protocol such as WPA2-Enterprise, but most of the people using WPA-PSK don't have the IT resources or the security expertise to move to a really hard to breech Wi-Fi network.
Oh well, be that as it may, if you're really worried about your network security, you're going to need to move off WPA-PSK just as you did when WEP (Wired Equivalent Privacy ) became hopelessly insecure. For now, I suggest that you move to WPA2-Personal. It won't protect you forever, but in the aftermath of WPA Cracker's arrival, it will do you better than WPA-PSK will.