I just migrated pool to another datacentre (longer story later...). There are three loadbalancers behind every of following DNS:
stratum.bitcoin.cz
stratum2.bitcoin.cz
stratum3.bitcoin.cz
So nine machines filtering the traffic right now. Balancers behind stratum.bitcoin.cz seems to be dead from the attack, but time to time I see some accepted connection. Once the connection is established, it will be kept by the balancer (that's nice advantage of Stratum protocol).
Please try these URLs in your miners, some of them will, at least after few tries, work for you.
stratum3.bitcoin.cz is working like a charm for me!

Same here....working on ....>>>stratum3.bitcoin.cz
Thank you for your continued hard work.
working on stratum2.bitcoin.cz , but with some strange issues described here:
https://bitcointalk.org/index.php?topic=178722and with problem to subscribe:
2013-04-18 02:16:24: Listener for "Slush" started
2013-04-18 02:16:25: Listener for "Slush": stratum2.bitcoin.cz:3333 18/04/2013 02:16:25, started OpenCL miner on platform 0, device 0 (ATI RV770)
2013-04-18 02:16:25: Listener for "Slush": stratum2.bitcoin.cz:3333 18/04/2013 02:16:25, checking for stratum...
2013-04-18 02:16:30: Listener for "Slush": stratum2.bitcoin.cz:3333 18/04/2013 02:16:30, no response to getwork, using as stratum
2013-04-18 02:16:41: Listener for "Slush": stratum2.bitcoin.cz:3333 18/04/2013 02:16:41, Failed to subscribe
2013-04-18 02:16:43: Listener for "Slush": stratum2.bitcoin.cz:3333 18/04/2013 02:16:43, IO errors - 1, tolerance 2
UN/PW it's OK
other servers have time outs.