Those of us with older Android smartphones were pretty bummed out to hear that our devices will not be able to run Facebook Home. Things are not as bleak as they appear, though. Facebook has just released an update to Messenger that will bring Chat Heads to most Android phones.
The new update will install Chat Heads to Facebook Messenger on Android devices running Android 2.2 or later, which means that unless you own a bottom of the barrel 3+ year old phone, the update should work on your phone.
I checked out the available updates for my phone and tablet, and both had a Facebook and Facebook Messenger update available, but after installing the update and testing, I have yet to see any Chat Head functionality. I only update about once a month, so chances are that both updates were old and the new one has not yet been pushed to my devices.