You understand that with a 250M valuation, the sale is going to have to be at 500M minimum. What "VC backed site with no business model either" is going to be able to afford that?

Don't know where do you get that understanding from. Google's current market cap is 112B, its total revenue (2008) is 21B. It used to be that price/sale ratio is 10 for startups, which means they need 25M revenue to be valued at 250M. Even if P/S is massively compressed these days, they still only need about 50M to worth that valuation. 50M sale for twitter given the usage is definitely feasible.

Good point, idk facebook? :/

The real time reporting of news is a very interesting thing, as well as their real time search results. There are multiple ways a company like Google could use that.

There is also the communication aspect, etc. that lots of companies would be interested in (i.e. communicating with users for web companies).

If you don't see business models for Twitter, you're not thinking hard enough. There are plenty of ways for them to make money.