One of the biggest AGS events recently was the release of version 3.0. This is the biggest change in the editor since it moved from DOS to Windows! The actual script language has changed very little in this new version (see previous blog posts for those wee changes), and so that part is reasonably painless in upgrading, but the editor is waaay different.
First, you need to download the .NET framework, which gives the new editor its standard look-and-feel, and saves CJ re-inventing the wheel. You can then run the AGS 3.0 installer (yes, it now has an installer!) or there is a zipped version if you prefer DIY installation.
So now you can have multiple scripts open at once (via tabs at the top of the page), you ran set breakpoints in the code, and single-step through them with the editor and game side-by-side, you can import editor plug ins like the great Media manager and the whole thing has a much more modern look to it. I'd really recommend going in and having a play, and CJ is particularly open to fixing minor usability issues as new people come to use AGS 3.0, so the 3.01 beta already has a lot of things fixed in it.
Another major point is the support for version control systems, like Perforce and Subversion, so large projects with lots of people working can all gel together better, and you can keep track of all changes to your game so when you say, "Oh flippety-flop, I didn't mean to delete that" you can cancel your checkout or go back to an old version of your code.