Problem:

The Fennec update showed up in the Update notifier.
I downloaded & installed it.

The Fennec icon replaced the Firefox icon on my desktop (I was running the last version of Firefox for Maemo available from the Firefox site).

When I try to start Fennec from the desktop icon, I get a black loading screen with the title "Fennec" and the whirly for several seconds, then it crashes back to the desktop.