I'd say, despite the halving of the block reward, I seem to mine nearly the same amount of MΣC. Thanks to the difficulty adjustment "preventing" Multipool and co from flooding the coin with loads of difficulty for way too long, I guess. Or Kimoto's Gravity Well sucking the hit-and-run load to oblivion.
This is a HUGE improvement for the dedicated MΣC community. Chapeau!
Most of the multi-miners probably don't even notice...but with the new difficulty adjustment formula it almost completely defeats the purpose of having it in a multipool. Along with other dynamic coins like CGB and CAP, so much time is spent jumping around it isn't even worth the lost work. As soon as one of them gets hit, one of the others becomes more profitable within a few blocks.
For example, there is someone mining at multipool.us at ~60 MH/s -- here is what they earned over the past 12 hours (including their share of about 140 Megacoin blocks):
At multipool.us: ~0.52 BTC
Had they been mining at wemineltc.com, mining strictly LTC, here is what their share would have been worth over the past 12 hours:
At wemineltc.com: ~0.63 BTC
So even though multipool.us includes LTC, the constant switching, lost work, etc is actually resulting in less profit for the miners in a lot of cases. It drives up the difficulty levels and results in dumping on the exchanges...which also lowers the price a bit. Too much importance is being placed on the current market price at any given second...but this doesn't always represent the true value. Somebody overpays for 5 Bottlecaps on Cryptsy? There's your new "price" and the multipools start hitting CAPS. Add to the fact that massive spikes in hash power result in a higher number of stale shares due to new block lag, and it really isn't doing anybody any good.
I think multi-mining will always be around...but now that coins are being updated with new difficulty formulas the advantage of multi-mining is diminishing rapidly. With the old formula, they were making a killing on Megacoin -- it was the perfect formula to be exploited on the multipools. As hash rate spiked...the difficulty actually started dropping for quite a while...and they could blast through a lot of blocks before it was no longer the most profitable coin to mine. With the new Megacoin formula alone, they multi-miners are going to take an instant hit on their profit margins. At first glance, it appears appealing...but once people start putting a pencil to it and realizing they aren't getting the return they thought, they will start to bail.