libindicate and libindicate-qt
This is not so much an issue as much as it is a statement and a question. I've done a lot of dinking around to see if I can fix the libindicate build. I've built the newest version of mono (which is not even in the testing repo for Arch) as well as building an Ubuntu version of gtk-sharp-2. Nothing seems to fix libindicate except removing the mono bindings as you've done or downgrading gtk-sharp-2. I did some research and found that nothing in the Unity-for-Arch build depends on libindicate except libindicate-gtk2, libindicate-gtk3 and libindicate-qt. I've also read that indicator-messages seems to have taken over the duties of libindicate. With all of this in mind, I decided to remove libindicate and libindicate-qt off my system. So far I've seen no trouble. Could it be that these packages are no longer necessary in the build order?
Make libindicate-qt first, and then libindicate
According to the PKGBUILD, libindicate-qt depends on libindicate. Does libindicate-qt build without using libindicate as a dependency? Are these packages really necessary?
I've done a lot of messing with this but have been unable to find a way to fix the error except for the fixes I've listed above. I've been using Unity for a while but I see no difference with or without the packages. I've also built pidgin-libnotify-ubuntu without libindicate-gtk2 and it seems to work properly. I get system notifications in the message bar as well as system notifications on my desktop (not the ugly box that pidgin-libnotify gives but the system notification box that integrates into Unity). So far everything looks fine without these two packages. Perhaps others could try this and let me know if they see any differences?