Patch 1.9 Test Servers are up once more for a second time in US Servers
Patch 1.9 won't be released to the public until January according to World of Warcraft Quest Designer Tigole. Some bugs are still under wraps, and it is possible Test Servers are opened once more temporarily to make sure a bug was properly fixed.
Tigole: " We were hoping to Patch on December 13th but we all agreed that 1.9 was not ready yet and still needed some tuning and bug fixing. So we made a few changes and fixes and released those builds on the PTR. Currently, the PTR builds are pretty close to what we're going to release. However, because of the changes we've made internally, the PTR build is now out of date. We don't really gain anything by leaving an old build on the PTR. We're probably going to bring the PTR's up one last time to make sure the sync bug is fixed and then bring them down again.
It is unlikely that we will patch during the end of Decemeber. We like to have "all hands on deck" when we patch so we can respond to emergency issues as quickly as possible. Players in North America tend to think of it as "patch day" but for those of us at Blizzard, it's more like "patch week". One day we patch Europe, the next the US, then Korea, then China etc. -- all on different days (this is done so that we don't bring down their servers during primetime).
If you wanted an ETA, my best guess would be very shortly after New Years"
