Facebook has big plans for something involving Android on April 4, according to an invitation to a press conference that the social giant sent on Thursday evening. “Come see our new home on Android,” it reads — whatever that means.

This event seems unlikely to showcase a mere update to Facebook’s Android app, as those typically warrant a blog post and not much more. Instead, Facebook seems likely to have bigger plans for Android.

TechCrunch’s Josh Constine, who was dead right about Facebook’s last announcement of its updated news feeds, believes that Facebook might be announcing a modified version of Android, specifically optimized for Facebook and designed for an HTC phone. That might well amount to the “Facebook phone” that so many people have been expecting for so long.

Of course, it would likely also present Google with another headache, should Facebook join Amazon in promoting a heavily modified — i.e., “forked” — version of Android.

But On The Other Hand

Suppose that speculation is off-base, though, and Facebook is just going to a lot of trouble to unveil an updated Android app. It could still have a few tricks up its sleeves.

Earlier this month, my phone asked me to update the Facebook app with the same message as AllFacebook described, offering to upgrade the app to a new version (2.2.1-g12, in AllFacebook’s case). The version number now sits at version 2.3. However, one of the permissions that the Facebook app asked for was to “download files without notification.”

That could herald a divorce with the Google Play market, as Facebook would then presumably be free to launch silent updates to Android phones without permission. In the most extreme case, that permission could conceivably allow it to modify Android on-the-fly for users. (Whether users would welcome that is another question entirely.)

One possible feature that Facebook could add, of course, would be to update the mobile app with the multiple News Feeds that it added to the desktop version just a few weeks ago. Those feeds segmented out Photos, games, music, and subscribed Pages, de-cluttering the main News Feed and giving photos more prominence.

That update, however, lifted the left-hand nav bar from within the mobile application and added it to the desktop version of the site, possibly meaning that the mobile interface will continue to drive Facebook’s design going forward. If true, then that means that we should expect future enhancements first within the mobile app, and only later on the desktop.

On Wednesday, Facebook also implemented an improved version of mobile ads. With these new capabilities, developer can reach specific versions of Android and iOS mobile operating systems and devices on Wi-Fi only connections, developer Calvin Grunewald wrote in a post. “For example, now you can reach Jelly Bean 4.2 or iOS 5.0 and greater with a different message based on what is most relevant to the people using those devices.”

Developers can now create and buy mobile app install ads through Facebook’s Ads Create Tool, the company added.