I've been demonstrating the IE Dev Toolbar for a while now to many of my customers. It's really great for helping web developers troubleshoot all of the tricky issues they deal with in the browser. It's even more useful when it comes to helping with the development of AJAX applications. If you've been using Firebug to help with testing your web sites in Firefox, then you'll certainly want the IE Developer Toolbar at your side when you do the same in Internet Explorer.
The IE Developer Toolbar betas (3 of them) have been out for a long time now. I must have missed this while I was on the road most of May, but the official version 1.0 release became available back on May 10th. You can go get the bits here. (More about how I discovered the new release coming soon in a future post.)
The 1.0 release will un-install any previous betas for you automatically. Be sure to close all instances of IE before the install.
The IE Blog is run by the Internet Explorer team. They provide all sorts of juicy tidbits and information about IE. It's also a great way to get your feedback to the IE team. The comment section on their blog is VERY busy... but they have people on the team who make sure to read through all of them!
The IE Developer Center on MSDN is a great repository where you will find links into all of the IE documentation that is relevant to developers. There are also links to different team blogs, as well as community forums where you can discuss anything related to IE development.