Released a day ahead of schedule because the features were ready, explained a Mozilla representative in an e-mail to CNET, Firefox 17 for Android supports an expansive list of ARM v6 hardware. This means that older but popular phones like the Samsung Galaxy Pro GT-B7510, HTC Status, Motorola XT531, and Motorola Fire XT can now run the alternative browser.
The hardware restrictions are fairly minimal, and appear to include many if not most phones still running Android 2.2. As long as your phone has at least an 800MHz processor and 512MB of RAM, it ought to be able to run the browser.
Other changes to Firefox 17 for Android bring better support for the visually impaired to the browser, as Firefox no longer requires additional configuration to work with the Android 4.2 screen-reading feature TalkBack. When installed on a phone that has TalkBack activated, the browser will automatically start working with the feature, which Mozilla says is a first for Android phones. Explore by Touch and Gesture Navigation are also supported.
Firefox 17 now includes the "sandbox" attribute for iFrames, making it a bit more secure; h.264 video hardware and software decoder support in Android 4.0 and above; and rudimentary support for Mozilla Marketplace Web apps.
The Firefox 17 for Android changelog has full details on what's new, changed, and being worked on.