Facebook has announced new features that could see the company become a central part of every cell phone app on the market.

One feature, called single sign-on, promises to make use of the fact that smart-phone users can be signed into Facebook’s app even if they’re not using Facebook at the moment. A blue Facebook button can be added by developers to their own apps to provide you access with a single click. It could sweep away the need to ever type a login and password for any other service.

That can certainly make life easier, and also make it simpler to share what apps you’re using with friends. More sharing is good for Facebook: it makes our news feeds richer and more compelling to friends. It also provides a broader awareness of our habits that could help Facebook’s real business: targeting ads.

A second new feature attempts to position Facebook at the heart of every location-based app, giving the company access to data that otherwise would be hidden inside other companies’ products. A new set of tools for app developers lets them tap into Facebook’s database of locations and what it knows about your friends’ movements. This means that people will find location-based apps more powerful because they’ll be able to access information about friends that don’t use the same apps they do. For example, people reading about a bar on Yelp will be able to see which friends visited the same bar, even if those friends don’t use Yelp.

It’s not just privacy-conscious users that may be a little unsettled by this latest extension of Facebook’s social tentacles. Today’s new services–and a new “deals” feature that allows businesses to offer coupons via Facebook Places–also bring it into direct competition with the same app makers it claims to be helping. Location-based apps like Yelp, Loopt and Foursquare have signed up for the new sign-on and location tools, saying their users will benefit. But Facebook seems to be pushing those services toward being mere front-ends for its all-powerful database underneath.