After securing further funding last week ($15 million raised valuing the company at $80million), speculation has grown over what direction twitter takes now to make it into a profitable company.
Many commentators argue that any commercial model risks alienating its users, yet a commercial business needs to generate income.
A subscription model is out of the question, so advertising revenue seems to be the only avenue available to them. I think the most likely outcome will be a buy out, with google and Microsoft no doubt willing to do battle for a micro blogging site that is rapidly growing in popularity. I would imagine that ads will be displayed down the side of your twitter page similar to ads on search engines, this being the case, google would be a natural buyer, given their history with other blogging sites and their interest in social networking. Of course, MS could always integrate it with their Live service and MSN. Either way, twitter as a technology is sound, even if their business model is not.