You all know about the new in-game calendar feature that came with patch 3.0.2, right? Right! The calendar has just been integrated into the Armory as well, and it's really quite cool. By logging into the Armory and clicking on the Guild tab, you can check out all of the events your guild has listed on the calendar via the interwebs. You can Accept and Decline event invitations right from the Armory, but I haven't seen an option to create new ones from there. That's something you'll still need to do in-game.
When I saw this on the official WoW website, I sort of rolled my eyes because the Armory hasn't updated my Shadow Priest's gear or spec in months. How can it possibly keep up with the calendar? I did a little poking around with it, and I was pleasantly surprised. I created a new event in-game on our guild calendar, and it showed up on the Armory about ten minutes later. I accepted the event on my alt on the Armory, and that showed up in-game almost instantly. If the features keeps that kind of stability long term, I will definitely appreciate having it. Little conveniences like this really help the community feel of guilds.
Now to bug people about integrating this into Facebook and the like.