Except, of course, since they're using Wordpress and have actually set up separate authors, it's actually built in functionality.
So, if you want to read all posts by Om, just subscribe to this feed: http://gigaom.com/?feed=rss2&author=om-malik
I feel so much happier now that I can have Om delivered just for me. That's not to say that postings by Liz Gannes et al aren't good (quite the opposite, in fact). But in my mind, the mixing of author posts was diluting the "voice" that I heard from Om. Not having interacted with the other authors as much, it will take me more time to recognize their voice and style as belonging to a particular person. Otherwise, it's just news.