It's still not clear what Grillo wants to do. The Government needs to get a vote of confidence from the Parliament (it's similar to the German system) and today Grillo said his party won't give a vote of confidence to anyone. And that would be extremely stupid. His movement could be the most important party, they could force the Democratic Party, which "officially" won these elections, to make some serious and badly needed reforms, but they need to give them a vote of confidence first and allow them to form a Government. Then they can threaten them to remove the confidence if they don't behave (that's what I would do), but if they refuse to collaborate, we only have 3 alternatives:

1) another "technical government"
2) new elections in a few months
3) a big coalition between the Democratic Party and Berlusconi's party

The third option would make me sick, but I think that's what Grillo wants, so he would be able to say "See? I told you! They're all the same!" Too bad it would be his fault if that happens. And the people who voted for him may be angry and fed up, but they're not stupid. At least, I hope so...