I just started using the Firefox mobile nightly build on my android tabet today. I have not been able to find a way to reopen/undo closed tabs. Is this feature implemented in the Firefox mobile versions?
This is not implemented on Firefox for Android at this time. I have poked the bug we have on file for this feature to see if we can get a timeframe to add it back.
This post actually inspired me to write my first add-on for Firefox Mobile. You can find it here