The Battle.net Forums have word that the StarCraft II Beta system requirements posted earlier were not accurate, as this was just a placeholder:

I just wanted to drop in to clarify the situation a bit. As has been mentioned above, some websites have posted system requirements for the StarCraft II beta that were not accurate. The page where this information was found was a placeholder that should not have gone up. We will have more information about the system requirements once the beta starts.

Sorry about any confusion this may have caused. We did not intend to troll you. =)