...can be found here.
Basically, the Firestorm developers have found the problem with operations that load or save files that cause the Second Life client (not just the LL client, I hasten to add) to hang in Linux if you try to save a photo to disk.
Now to go over and see whether I can be a beta tester if I make puppy eyes at them. :)
UPDATE: No need. I am now running Firestorm 18.104.22.168744, and I can save a photo to disk. Please, people responsible for other SL clients, adopt this fix ASAP.... and thank you to the Firestorm developers. The grid is in your debt.