I read a little about Ethereum (only so much), sounds like a good idea.
One question came to mind however. If a "Contract" can contain its own memory and executable code, is there going to be a security issue? I could imagine someone writing a virus inside a contract, for example. I'm guessing that the code in a contract would be executed by all network participants. Therefore there's going to be a need to lock-down the scripting language, right?
Please clarify, maybe I'm misunderstanding it!