Yes some really interesting changes. AH is going fully cross-faction to alleviate economy issues when one faction is stronger then the other. Now you won't join a server where you are one of a few Alliance and find the AH empty as dirt or heavily overpriced.
They are also removing guild levels. Guild PERKS will still exist, and you will still get things like banks, missions, achievements, etc... The reasoning was that leveling became more of a barrier for new guild creation then a boon, and so now just being in a guild will give you all the various perks.
Also tonight I finally logged on to try out the suicide mission. The nostalgia level of this expansion is intense. You first have to close the portal, which the Iron Horde is using a captured Gul'dan, Cho'gall, and Teron'gar (Aka Teron Gorefiend) to power it. You free them as it's the only way to close it, stranding you there. A whole bunch of randomly named heroes are down on the front lines and it's assumed once you flee that all of them die.
Your group is made up of Khadgar, Thrall, Maraad, Ariok (Eitrigg's son), Lady Liadrin, one of the named Warden from Firelands (blanking on her actual name), a named Druid of the Talon (though not the cool one), and a dark iron demo squad. You work together to save both orc and draenei slaves including Drek'thar and Maladaar (remember him? last boss of Aurchenai Crypts) and try to escape the massive iron horde army. The only one I remember dying was Ariok, who sacrificed himself to save the group from Kilrogg.
While you flee the whole thing is pretty much a Warlord Rollcall. You start fighting Bleeding Hallow bloodmages who are stealing blood to make super soldiers until Kilrogg shows up, forcing you to flee. Then you get stuck in an arena with Kargath sending his super sado-masochist army to kill you, which you have to escape. Next you move on to the Shadowmoon, who have taken up rift and void magic, and scare of Ner'zhul after killing his lacky Keli'dan the Breaker (Remember him? Last boss of Hellfire Blood Furnace). Then the Blackrock, who are basically the engineer clan making all the super-machines, until Blackhand shows up and you have to flood his forge. You finally end it by destroying the portal and seeing Grom show up as you escape the vast army.
It's actually really well done. Makes Khadgar look like a badass too.