Hackage finally came back up, but I ran in to trouble with some guy called trhsx. Every time I tried to ‘cabal install happstack’ I got the following error:

Configuring hsp-0.4.5...
Preprocessing library hsp-0.4.5...
Building hsp-0.4.5...
ghc: could not execute: trhsx
cabal: Error: some packages failed to install:
happstack-0.3.2 depends on hsp-0.4.5 which failed to install.
hsp-0.4.5 failed during the building phase. The exception was:
exit: ExitFailure 1

After some digging I found out that I was supposed to have ~/.cabal/bin in my path, who would have thought? Anyway, I added the following to my .bashrc:

PATH=$PATH:~/.cabal/bin

…and happstack installed without a hitch.

Win!