Twitter is actually the only "social network" that I use daily and find real value in so I really hope they can get their act together somehow.
Just a few more random thoughts... Twitter's biggest asset is its core product and they should not meddle too much with it. And I think they should be able to make a company profitable with just that.
Even though the product itself is really simple, there are many use cases of it that are not all easily transformed into revenue and probably not so easy to communicate to investors.
Its basically a platform that enables a new form of communication. Different people use it for different purposes. Companies use it for different purposes. Traditional media gets lots of their content from Twitter nowadays.
Mimicking Facebook in any way would be a mistake because I think it's a fundamentally different product.
Just a little more info: If You follow many users, sometimes You don't want to scroll through all unread tweets in your Twitter stream and just want a quick look at the most "relevant" stuff tailored just for You. So I created a little app for that