As an example, Yesod doesn't work on the raspberry pi, because GHCi is not in the debian ARM repositories. This is annoying, because compiling everything yourself takes forever on the raspberry.
It should be noted there is a difference between "not in repos, so I have to manually build, but it works" and "there is absolutely no way to run this software on this platform due to the processor".
It is really promising for the current software written against glibc and friends to have all these arm devices running homebrew ARM builds without many hitches.
Especially compared to a platform like, say, Windows, where even though there is an ARM version (Windows RT) which is extremely stripped down and awful on all fronts, there is no software for it because of API compatibility issues and the fact that without open source recompiling most of the Windows software catalog is impossible.
Ah, interesting, had actually looked into GHC and knew there was no GHCi support for ARM (also, ARM is only a Tier 2 platform), but did not realize that made it impractical to use Yesod. That kinda sucks.
