I cannot imagine that LTC is added in times like these. Who knows what the effect on Bitcoin would be if major exhanges suddenly trading LTC. If Bitcoin price is severally affected, I can imagine the anger.
BTC-E is running a multiple coin exchange for quite some time now and it works like a charm.
I think everyone will benefit from adding the #2 coin to mt gox.
And: More trading = more fees = mt gox happy