It is my belief that Satoshi has spent at least some of his Bitcoins. I think he (or the team behind the name) did so in June of last year and possibly February of this year. This is from analysis of Bitcoin Days Destroyed. I also think a significant player (perhaps Satoshi, but probably someone else that is/was a major player) also sold a significant number of Bitcoins in mid-November in order to combat the bid-waller. I'm not entirely certain why as they did so at a significant loss evidenced by the subsequent rise over the next few months.
It also appears from Bitcoin Days Destroyed that an old miner also moved coin in mid-February of this year. It appears that it was used to game Bitcoinica. It is probably this person that I'm interested in the most due to the fact that they seem to be privy to Bitcoinica's business model and gamed it quite efficiently.
These are, of course, unconfirmable, but that's what my amateur analysis leads me to believe. I'd welcome anyone to look at the evidence of what happened with Bitcoin Days Destroyed at these three points in time and events surrounding these dates to corroborate what was going on.
Evidence: (very old miners, June 2011 and February 2012)http://blockchain.info/charts/bitcoin-days-destroyed-min-year
(somewhat major miners, November 2011)http://blockchain.info/charts/bitcoin-days-destroyed-min-month
I know there has been talk of this mystery miner that has been mining huge amounts without including transaction fees:https://bitcointalk.org/index.php?topic=67634.0
Given that in February someone sold a significant amount of old coin (>1 year in age), it is entirely possible that this was Satoshi or an older miner that then spent that money to set up a huge sASIC or FPGA array that we now attribute to this mystery miner starting in early March 2012.
These are just suspicions. I want to make it clear I don't claim to know anything for certain, but it would not surprise me if these were related.
Even if the MM is Satoshi (or the group we call Satoshi), I'm 100% behind these actions as they continue to nurture Bitcoin in new and interesting ways.