As more and more journalists are on Twitter, this might be a good way to follow and build relationships in your pitching efforts.
I just discovered Muck Rack
, an online site that lists journalists who are active on Twitter.
The basic idea is good, but you still have to do your research: is the journalist who is Tweeting away appropriate for your pitch? If you are pitching technology, you probably won't want to pitch the travel Tweeter.
My suggestion is that before you engage, much less pitch, you might try following the person at the appropriate news site you are hoping to gain coverage in. Sometimes a simple phone call or brief email pitch (though somewhat old school) can still work and be very effective.
Your Tweeting (or Mileage) may vary.