We haven't seen much PTR action in a little while (although I guess the beta realms are really a PTR for Wrath). That may change soon, though: the European PTR forums were just wiped, and Tigole recently said "3.0 will be on the PTR's soon." Disregarding his apostrophe abuse, and Blizzard's colorful history with the word "soon," this does conspire with the forum wipe to indicate that the PTRs will probably be up with this pre-Wrath patch within, I'd say, a week or so.
What does this say about the Wrath release date? Well, I'd say nothing, really. In the same post, Tigole mentions that some patches were on the PTR for over two months (which is good because a lot of the new talents are really half-baked right now). Additionally, 3.0.2 could come any amount of time before LK. 2.0.1, the pre-Burning Crusade patch, came a bit over a month before BC was released.
There is one notable advantage to bringing 3.0.2 to the PTR as soon as possible: more testing. While a fair number of people are in the LK beta by now, everyone who wants to (and had an active account the last time the PTR authentication server was updated) can access the PTR. As I mentioned above (and as Tigole agreed in his post) none of the classes is done yet, and the more people we get play-testing them, the better.