For years now, Facebook has offered quite a few ways to access the site from mobile devices, and they’ve proven immensely popular. In February 2010 the site had 100 million mobile users per month — today it’s announcing that it’s up to 250 million. To coincide with the growth stats, Facebook has some other news to announce about mobile.

We hear most often about Facebook’s native applications available for iPhone, Android, WebOS, and other app platforms, but a significant majority of mobile users actually access the site from the web. And up until now Facebook’s web setup has been a bit complicated: users on smartphones like Android and iPhones have been directed to touch.facebook.com, which is optimized for large touchscreens. And users accessing the site from a featurephones (and there are a lot of them) would be directed to the more plain-looking m.facebook.com. Today, that’s changing: Facebook is merging touch.facebook.com and m.facebook.com into the same site.

Now Facebook has launched a new framework based on XHP, Javelin, and WURFL that uses the same underlying codebase, while tweaking UI elements on the fly depending on what device you’re accessing the site from.