There are some. For example, Maemo WordPy is designed for blogging. SharePy alllows multimedia uploads to Facebook, Flickr, Picasa, Youtube, and others. Friendscard is a Facebook client. Pidgin On Maemo supports IM. Mauku supports Twitter.

Unfortunately, many developers have moved on to the N900 so, unless you want to write a new app, I wouldn't expect much more for the N810.