Identi.ca doesn’t yet support turning notifications on/off for specific users.
Until that’s ready, subscribe to the individual RSS feeds for people you’re particularly interested in (and keep these feeds in their own category). They update pretty quickly, and if you’re in Google Reader all day like I am, it’s a great way to catch conversation from your friends without simply refreshing the page.
If you aren’t already aware, you can also subscribe to single RSS feed of everyone you’re subscribed to – just go to your “Personal” tab and subscribe to the feed for that page.
