(Modders who want compatability advice, look here. Still, depending on your needs, it may be perfect.
In my testing it works, though it has some glitches, especially with dll mods and Vox Populi. If you want a much more user friendly tool, check out, which I think is based part on MPMPM. The idea is that by packing all the mods you want to use into something that looks like a dlc pack, Civ 5 can be tricked into loading the mods on start, and then you can play it with mods in multiplayer through the standard multiplayer interface, but only with others who have the same fake dlc pack. It is not terribly user-friendly, but it works quite well, and without the strenous limitations that Jaii der Herr's more user-friendly project still has. The intent of this thread is to provide Civ 5 mod users with the ability to play their favorite mods in multiplayer.
Actually, Gedemon has PM'd me, and I guess I officially have permission now. The creator of the original thread and code, Gedemon, is no longer active on these forums, and there have been significant updates in the meantime, I am making a new thread with an updated first post.