Blizzard has posted the schedule this week for testing of the new bosses in Icecrown Citadel on the patch 3.3 PTR. Here's what Slorkuz on the EU forums says is going down:
October 21 at 7PM EDT / 4PM PDT - Festergut
October 22 at 7PM EDT / 4PM PDT - Icecrown Gunship Battle
October 22 at 19:30 CEST - Icecrown Gunship Battle
As always, these schedules and everything else on the PTR is subject to change at a moment's notice. You can find short descriptions of what we know about the bosses after the break.
Patch 3.3 is the last major patch of Wrath of the Lich King. With the new Icecrown Citadel 5-man dungeons and 10/25-man raid arriving soon, patch 3.3 will deal the final blow to the Arthas. WoW.com's Guide to Patch 3.3 will keep you updated with all the latest patch news.
According to the recent Icecrown raid preview that Blizzard gave us, Festergut and Rotface are to be found in the Plagueworks wing of the citadel -- they're two wacky experiments that one "Professor Putricide" has assembled for protection. They're also called "new forms of abomination," so expect lots of guts, disease, and green stuff that you probably shouldn't be standing in.
As for the Gunship battle, we heard a bit about this back at BlizzCon earlier this year. It should feature two different encounters, one for each faction, and you'll square off against the other faction shoulder-to-shoulder with some of your factions heroes. Oh, and apparently you travel between the two airships... using jetpacks. Should be a fun encounter to test -- we'll try to have some impressions of these fights later on this week.