Our pool wallets have been updated and right now have the only chain that goes past block 855838. Coins mined there will be valid and spendable once the exchanges convert their wallets over too. The network is getting hammered right now with traffic because of the artificially low difficulty of the older version wallets that are still hung on that block and think that over 6 hours have passed without a new block. Once everyone updates their wallets things should normalize.
I'm rescanning the chain for the block explorer ultrabex.com. It will hopefully be current in the next hour or so.
Here is the latest wallet source:
https://github.com/Kracko/ultracoin-2.gitAnd here's the new Windows Wallet -
http://www.tumblingblock.com/ultracoin_733_win32.zipYou will have to manually shut down your old wallet and it will take awhile to convert your existing blockchain data to the new format on the startup and also reindex it using leveldb. This could take a few hours and it will appear to be hung. Just let it do its thing. You can peek at the debug.log for progress in this directory C:\Users\<your username>\AppData\Roaming\UltraCoin.
md5sum ultracoin_733_win32.zip
e588e055f5767a45edb6e66a3092e283 ultracoin_733_win32.zip
I will be putting together a Macintosh wallet package as well, hopefully that will be finished by tomorrow evening.