Judd Vinet: Time is a huge one. Arch doesn't pay any bills for myself or other developers, so we typically can't work on it during the "make some real money" hours of the day. Lately I've been doing contract work, so I shift my schedule to try to be available during the days, but it's still tough to keep up.
The growth of the community and userbase means more bugs, more feature requests, more lines of communication, and more PR work. Somewhat surprisingly, the development team has met this growth head on and we've handled it quite well. We've always been wary of growing too fast and I think that's been a good thing.
Jan de Groot: Time and motivation. We're not getting payed for our work and lately I've been very busy with other things.
Tobias Kieslich: Speaking of general things, time is a limiting factor. Beside some real life and pay the bills kind of work that needs to be done, I wish I could spent more time on ArchLinux. And sometimes it's hard to make a decision to do some package improvement or to take the guitar and play some tunes.
On a more technical sides, API changes are always a challenge. Was it the freetype2 header change some times ago, that required to touch many packages to include the headers correctly, or most recently the db package with the transaction support. One always run into the risk to break packages. Meanwhile we have the testing repository, to catch much of this trouble before it goes online. But the work needs to be done nevertheless.
Damir Perisa: One of the challenges to me is to provide many good scientific software to the community. One of the points to solve was, that we lacked the GNU fortran compiler and some packages like octave and R do not really like to be compiled with f2c. Since we have gcc-g77 now in the repositories, this challenge is now easier to face.
A not yet solved challenge is to find a standardised way to handle additional java software. Also i plan to write on the documentation, but besides university and other activities i hardly can find some time to spend on it.
Dale Blount: Time. Since we're all volunteers our "real jobs" come first and sometimes we're found lacking the needed time to update packages and to improve Arch.
Jason Chu: Keeping interest. Previously I maintained way too many packages that I didn't use. Each person has a set of packages that are their need-to-have set. If you maintain too many need-to-have packages, you find you're always rushing to get things done. Very tiring.
Tobias Powalowski: Time is the most important factor. We are not full Arch workers and all have their own jobs, studies and so on. We give our best to make Arch as up to date and stable as possible.
The most problems are when a package will not compile anymore and you will have to search for patches or write the patch on your own. Or you have to look for ways that people can have a clean update of their systems, without getting too much trouble while updating.
Aurelien Foret: Time! I'm not working on Arch for a living, and as consequence I have to find a balance between the time I devote to Arch and my social life.
Arjan Timmerman: The biggest challenge is finding the time to do school/archlinux and World of Warcraft.