Quick fix: overwrite ModLoader.class with ModLoaderMP's version. Forge's version is bugged atm and should be fixed on the next version (1.3.2).
Okay, I did that and still broken. Other things that are bugged at the moment, I can not pick up lava/water with buckets or cells.
I replaced first the servers ModLoader.class and nothing, so I tried with the client side as well. Still nothing. 
Just found out, voltage transformers do not function, nothing goes through them.
Update: This morning I decided to redownload/install everything again to double check and see if I could get things fixed before anyone tried to play on the server. Installing it fresh the way you suggested (using just ModLoader.class from ModLoaderMP) did indeed fix the lava/water bucket problem, but I could not destroy any block. O.o anything I tried to destroy just reappeared a few seconds later. *laugh* So I dumped the whole ModloaderMP after forge, and made things work more or less again, seems I had done that from the start. But I think an inability to destroy/get any blocks is a worse alternative. *laugh* (and yes I know near the original spawn spot you can't get any blocks, I went to our treefort in progress, and then far away from that as well to test.)
Backed up my server, installed fresh from nothing, ModloaderMP, Forge, fresh world/config files and all=server will not start.
Placed ModLoader.class in from ModLoaderMP, server starts= Walked for a while in a random direction, can not break any blocks, (gave myself op and still can't)
Placed ModLoaderMP after forge.=Server runs, can get/place blocks with no problem, but can not smelt anything from IC2 in a normal furnace, can not pick up lava/oil/water, transformers do not work.
So, yeah guess I have to wait for IC2, Buildcraft and red power update to the new forge? Patiently waiting. 
Downloaded the newest forge version, server won't start, hehe. I replaced the ModLoader.class with the new one in forge, and it didn't change anything.