Smug satisfaction here..
I won't be using it, because I'm a smug git, and have something better. I bought a license for Bibble Pro for about 50 quid, because I needed something that understood Leica raw format, and wasn't restricted to 24 bit colour internally (like wot GIMP is if you use the raw importers people have written for it). All of this ruled Picassa out, of course.
Bibble is a revelation, and has some absolutely killer features specifically tailored for "digital darkroom" tasks, batch processing and other stuff. I prefer it to using Leica's own imort filter for photoshop, unless I actually need to do something dastardly to the pictures in question. Great software- huge time-saver and fantastic results too. The chromatic aberation and lens distortion compensation (which compensates with great specificity) on their own are worth having, even before you consider the insanely good raw support, the reassuring non-destructive workflow and and all the other fantastic stuff.
Of course, the biggest benefit was that buying the pro version grants you a license that lets you run your software on mac, windows or linux (as well as nifty multicore support), so I have it installed on all three, and can crunch the output of my camera at home or work, whichever computer I'm on. Brilliant software- and multi-platform licensing always makes me feel less screwed. I really feel like I got my money's worth for this great software- oh, and the support is good too. Oh yeah, and the much-threatened v5 is on the way this year, and is looking quite spangly too.
So, if you find the free alternatives aren't quite cutting it, give Bibble a go, and maybe you can be as horrifyingly smug as me. Oh yeah, and you'll be getting great pictures from your camera in a short time, too- side-benefit :)
Paris, because she approves of touching up.
(People who are happy with Picassa, good on you)