In my previous post 3rd party MSN problems, I discussed how to update pidgin to use MSN-Pecan, rather than Libpurple. After doing some research, the problem was found to be the implementation of MSNP15. Official MSN clients, as well as a few 3rd party clients, seem to fall back on older protocols. As MSN-Pecan uses MSNP12, it will work.
This morning, I accidentally signed in under MSN, rather than the WLM account on pidgin and lo-and-behold it worked! The pidgin folks have pushed out a fix to the MSNP15 problem and pidgin should function correctly now.
If you’d like to follow the bug report, it can be found here.