Facebook is expected to make a long-awaited announcement this afternoon about how it will be integrating real-time location data. We'll be live-blogging the specifics of the new features and touch on the meaning for other location-based social sharing services like Foursquare and initial reactions from pundits and the typical Facebook user.

The announcement is expected to come around 5 p.m. Pacific time. Read on for the highlights. You can also watch the announcement live.

5:13 p.m. And we're live. Randi Zuckerberg, Mark's sister and director of marketing at Facebook, says Facebook is going to talk about new features, how it affects developers, open up to questions and then broadcast from the "after event."

5:23 p.m. Mark Zuckerberg nervously introduces. "Today the thing that we're going to be talk about is a new "places" product that we've been working on for a few months... a while." Anecdote about how he and his girlfriend were eating dinner, testing the new Places feature, and realized a friend was eating at the restaurant next door at the same time.

5:29 p.m. Each place has its own page and "here now," which shows who else is checked in. Places is very focused on real-time. If a friend checks in nearby, you get a notification.

5:30 p.m. Michael Sharon, Product Manager for Facebook. Places is launching on advanced mobile browsers.

5:34 p.m. You can tag your friends when you check in to a place. You have to allow proxy check-ins to have them post to your profile, but they'll still post on the place page regardless.

5:38 p.m. Talking about privacy now. Default for check-ins is "friends-only." You can remove any tag or check-in. You can opt out of being tagged in others' check-ins.

5:40 p.m. Read API coming tomorrow. Write/search APIs in closed beta.

5:41 p.m. Sharon invites "partners," Scott Raymond from Gowalla takes the stage!

5:46 p.m. Holger Luedorft from Foursquare. "This basically validates that we're on to something" with check-ins. Says they'll continue to work on the Foursquare platform and looking forward to leveraging the Facebook Places API.

5:49 p.m. Eric Singley from Yelp and Keith Lee from Booyah, which made a new app in three weeks using the Places API, called InCrowd for iPhone.

5:52 p.m. You can email questions to fbhqlive@gmail.com.

5:56 p.m. Facebook's Chris Cox talking about how technology is encouraging interaction in the real world and forming a living history - imagine getting a push notification: "this is where your parents had their first kiss, here are the photos, this is what their friends said about it" - or something like that. "One day, when it's done, you'll go to a page and on that page will be our collective memory [...] that's dope."

6:00 p.m. First question is about privacy. What if someone makes my apartment a place on Facebook? You can report it, Facebook says.

6:01 p.m. Second question, from Mashable's Ben Parr - What about monetization? Zuckerberg himself answers, saying basically, we're developing the feature to be useful to people first and then monetizing later.

6:02 p.m. No updates planned for Terms of Service related to Places.

6:04 p.m. Business owners can claim ownership of a place and it becomes a business page.

6:07 p.m. No support for checking into television shows, movies or "viewing events."

6:14 p.m. And the presentation wraps, but interviews with Gowalla, Foursquare, Yelp and Booyah as well as more Facebook engineers are coming. We're also sending question to Facebook and we'll update with the response and more analysis of what Places means for users, developers, existing location services, as well as online privacy and monetization of the social web.