Jakob Neilsen recently published research on usability evaluations of social networks and RSS feeds. Summary:

As the satisfaction ratings indicate, we have a long way to go to improve the usability of social network messaging and RSS feeds.

The problems start with something as simple as the choice of username. For example, the United States Department of Education's Twitter ID was "usedgov," which sounded to users like "used government" and was off-putting. Logos were often bad as well, particularly in the small rendering that some services offer. Users depend on the ability to scan down a stream to pick out logos and user names, but this basic need was often thwarted.

The shorter the message, the more important the writing. Don't simply repurpose the first N characters of a longer piece of content. Too many corporate feeds didn't bother writing for the medium and suffered accordingly, as users didn't know whether to click the links (and therefore didn't).

The good news is that we can only go up. Users do want these messages. In moderation. If they're good.

"Usedgov" - Ha ha, Love it. If the feed in question was simply about repurposing existing content without re-working it, then in one sense, it is "used govt." - Announcing our Twitter account: get yr slightly used govt content here folks!

Seriously though, looks like this study covers good practical issues to keep in mind when setting up our own social network presences.