PSA: The Bitcoin blockchain has experienced a divergence between versions 0.7 and 0.8. Do not move your Bitcoins or they might be lost. Updates to come momentarily.
Update 1: So here’s the gist of it. The updated version of Bitcoin, 0.8, is able to handle larger block sizes. The miner’s using 0.8 mined a block that was too large for 0.7 miners to handle. This has created a divergent blockchain meaning that 0.7 miners are mining one chain and 0.8 miners another. There is an emergency fix being put into place. Right now it looks like miners running 0.8 are being asked to return to 0.7.
Do not move your Coins! While this is going on your coins might be lost so do not move them. There is discussion of halting trading going on – more to follow.
Update 2: Looks like the final word is against 0.8.
Update 3: I’m admittedly a bit late to the game on the blockchain divergence. TheBitcoinTrader has an updated post with timestamps:
Update 4 11:18 EST : Here’s current guidance for Bitcoin users – If you are not mining then you do not need to take any action currently, it does not matter if your wallet is version 0.8 or version 0.7. If you are solo mining or running your own pool than the current guidance appears to be to go to version 0.7 to run your pool or mining server – do not user version 0.8 for mining. More to follow.
Update 5 11:26 EST: MtGox has temporarily suspended deposits but looks as though it’s still allowing trading. BetsOfBitcoin just announced that they’ve brought their site back online as they feel the blockchain has worked itself out.
Correction – MtGox is still trading just not allowing deposits.
Final Update 12:18 AM EST: It looks as though the devs are working closely with major mining pools to get this resolved. It is going to take a bit of time to get the whole thing sorted out. I still suggest not making any transactions until the blockchain has worked itself out. If you make a transaction it should figure itself out eventually but to be on the safe side I’d say wait a bit. The previous update suggesting that miners switch from 0.8 to 0.7 is still correct. The 0.7 blockchain is the one that is being kept as it is the easiest/best fix at the moment. I’ll put together a synopsis of this tomorrow but now I’m headed to bed – the girlfriend is pissed that I’ve spent all night glued to IRC and MtGox.