First up: ReadWriteWeb calls out Facebook’s Twitter envy. I’m with them… Why does Facebook want to be Twitter? There is already Twitter. Twitter has a totally different core competency than Facebook. Why is Facebook trying to change their own core competency to compete with something that has such an unproven revenue model?

On the other hand, competing with Twitter has forced Facebook to open up it’s Stream with an API. Now, can I start liking my friends posts in the iPhone app? Okay, I know, really this move was made so that 3rd parties can develop (or add onto) their own apps to help Facebook be as cool as Twitter is with their API.

But beyond the arms race with Twitter, the stream API will open up the possibility for many new applications both within Facebook and outside its walls. An obvious one would be better filtering options for your activity stream. It would be simple to create an app that shows you the most liked or most commented on items in your stream, for example. Or now that stream can be plugged into various social search engines to give you socialized real-time results. Hell, if I could just search my own activity stream, I’d consider that a giant leap forward. But Facebook still only allows developers to cache data for 24 hours, so you wouldn’t be able to build a very powerful search engine or return results from more than a day ago.

Facebook has also become not just an OpenID provider (issuing party), but also a relying party. I believe they’re the first big site out there to do that. I’m not sure why all the others haven’t, because honestly, it’s kind of annoying to have 20 different sites that provide OpenIDs but if no one accepts anyone elses OpenID then it’s pretty much useless.

I’m glad that Facebook is opening up, but here’s a couple more things they can do to compete with Twitter (and/or make me happy):

• Allow tagging of friends in status updates
• Allow users to view a feed with ALL updates from ALL friends
• Try to make more content viewable on a single screen of the iPhone app
• Start rolling out vanity URLs to users in order of when they joined Facebook