Facebook will today announce the addition of a series of new features on its website, which are thought to include a Foursquare-style ‘places’ function that can be integrated into third-part applications. This is going to be big.

According to the FT’s techblog, the company is today hosting an event at its US headquarters that will “provide an update on the [its] features and products”. The additions and improvements to the site are part of Facebook’s defence against Google’s soon-to-launch social networking initiative. That might or might not be called ‘Google Me’.

At the top of its list is believed to be a hotly-anticipated location feature – Facebook is relatively late to the game, with rival Twitter announcing the launch of its own location-based service during the World Cup.

Speculation has been rife in the media, including in a piece on CNET last week that predicted that according to “multiple sources”, the geolocation “check-in feature at Facebook is slated to debut within weeks”.

The service will likely be an application programming interface for use by third-party apps, “integrating existing “check-in” start-ups more deeply into the massive social-networking service and in turn permitting location-aware data to become a part of existing platform applications”.

To what degree Facebook’s Places feature will compete with the likes of Foursquare, which recently announced a $20m expansion drive, and Gowalla is unclear. But a piece on GigaOm reckoned that it will be more than a mere “checking-in and getting badges” service.

The article said: “They will almost certainly involve user-generated content such as photos and videos, as well as Yelp-style reviews, all tied to a location (Hot Potato also aggregated user posts and media around places and events).

“Facebook will likely allow Foursquare and other location services to feed data from their platforms and users into the social network, provided they want to abide by the terms of the API and the open-graph protocol.”

Later today all will be revealed. But will the (likely) launch of Places, not forgetting the other changes and improvements Facebook will announce, be enough to protect its social networking dominance from aggressor Google?

Given that recent failed Google initiatives such as Buzz (it stares at me from my Googlemail homepage and I ignore it) and Google Wave (the latter was ditched earlier this month for being so obtuse that even its developers didn’t know what it was for) have failed to set the world alight, Facebook may have nothing to worry about and the Places launch will only serve to deepen its entrenchment on the social networking battleground.