So... yes that was a sudden announcement; as you may have guessed we had expected to have a little more time to prepare the release before it went out. Anyway, lets address a few questions which have arisen:
First question everyone asks, is when. Short answer is I don't know; the plan is a couple (that's approximate, no you can't hold me to exactly 14 days) of weeks after we have a stable beta. As we set these things by block number, the date will still be slightly approximate.
This leads to the obvious next question; when is the stable beta? Well, with regards to the reference client, the code in Github is looking fairly good at the moment (in fact, if you're running testnet infrastructure, please consider upgrading now), I'm about to start relay tests on the testnet to verify stability under load, mining stress tests have already been done for conventional mining, live network tests should start in the next few days presuming no major issues in testnet. The Android and Multidoge clients will need to be updated as part of this fork, however, and that's still a work in progress.
More critically, we only have two pieces of open source pool software that we know will build AuxPoW blocks; p2pool and Powerpool. We really want to get NOMP to support AuxPoW as part of the update, and so far that's still in early stages; if anyone can help there please do drop by the #dogecoin-dev channel on Freenode and ask what the current state is.
What does this mean for miners? Well, you can continue to mine directly on the Dogecoin blockchain, or you can move to a Litecoin pool that supports merge-mining. Given that pools have to do a software upgrade to switch, I'm expecting there to be a stepped transition from Doge-only pools to merged pools.
Strictly, AuxPoW will accept any blocks with the required difficulty (and apologies, I have previously stated it was tied to Litecoin, and it's not), so in theory you can also mine any other Scrypt coin and submit their blocks to the Dogecoin chain as well if you find blocks at a sufficiently high difficulty. Some pools may want to explore that option just in case their miners find high-difficulty blocks by chance, but the odds of doing so aren't good.
Lastly, what does this do for 51% resistance? Well, that depends on a few things, such as how quickly AuxPoW is taken up. As I've said above, it looks likely we'll see a ramp-up of AuxPoW over time, rather than a "big bang" switch over. As AuxPoW kicks in it will increase the difficulty (although never to the same level as Litecoin due to blocktime differences), and as difficulty increases the hashrate to 51% the coin increases. We're bringing this in now specifically because it gives us time to ramp-up. There's further improvements to the client being evaluated to better leverage AuxPoW as a security tool, however for now we're focusing on getting the fork in and stable.