This is important news. First, it signifies that Blizzard is at least comfortable in stopping the testing of PvE content. This might not be the best news for those that were still engaged in PTR activities; or for those that think there are still serious concerns regarding the content and class changes. We might be seeing the Druid Cyclone nerf stay.
Secondly, we can infer that the two stress tests they've held might not have been everything they wanted. If they're asking for more testing we can make an educated guess that Blizzard either did not see the kind of numbers they were hoping for, or they have made additional server changes that warrant additional tests. Judging from the lack luster stress test that went on Wednesday night, I'm leaning towards the former as being the reason for the change.