Some pools have mentioned that they support it here in the forums, and some may list it as a feature on their sites, but in general I don't think it's well documented. I haven't added any output to explicitly indicate that the server supports rollntime, but if you run with the -v (verbose) flag, you will see when the miner gets new work, which should be a pretty good indicator. The normal phoenix gets work 2-3 times per minute on my system, at 410MH/sec, whereas this version will get work once every 4 minutes (on servers that support rollntime) unless the server explicitly specifies a work expiration (for instance, Eligius sets expiration to 120 seconds).

Anyway, I'm glad to hear that it's working well so far! Some time, perhaps later this week, I'm planning to add some functionality for the software to try re-submitting work that fails due to communication errors / timeouts; currently any such work is treated as a reject and discarded. After that I may add some other little tweaks to make the software a little bit friendlier. I'll update this thread as soon as I add any new features.