Facebook unveiled Places, their new location element that allows users to check-in to venues. And, joins the startups like Foursquare, Gowalla, Loopt, and dozens of others. The next question is "when will Twitter follow suit?" Wll, in the meantime, you can try "Firefly iPhone app," with it, you simply sign in with your Twitter account and start checking-in to nearby venues.
You can also see where your Twitter friends are based on their Firefly check-ins or based on their latest geotagged tweets. That's a nice touch. And you can filter location to the city, neighborhood, or "nearest" level. Before you check-in anywhere, Firefly asks if you'd like to attach a picture to the check-in.
Firefly: App Store iTune