I'm still playing with P2 - Automattic's new(ish) twitter-like interface. It's buggy. Messages are defined from the beginning as "status updates", "blog posts", "Quotes" or "Links", some of which correspond to wordpress categories. Status updates do not receive a title, or rather, a title is not shown on the page. If you go into the dashboard editing interface, a title appears in the title box. This is an extract of the first words of the status update. Any editing done in the dashboard brings back a title, just like a blog post. Even if you remove the title from the title box, wordpress then recreates a title from the text extract, and this appears on the public version of the site. It may be better to always create status messages as "blog posts", but choosing to write a blog causes P2 to automatically mis-categorize the post as a blog post, rather than a status update.
So the P2 theme is actually more like a hack than something that Automattic has thoughtfully worked into the interface. Actually, I think it would make more sense for blogging software to work the categories of links, status updates and posts directly into their interface, in a similar way that Facebook does this; except that it should be possible to incorporate all of them on the same page. I could imagine a 3-column page theme that would do this in a satisfactory way.