One of the most critical features of ColdFusion Builder, in my opinion, has been its extension API. ColdFusion Builder 2.0.1, currently in beta, adds some very nice updates to the API, including...

• Extensions can get a list of projects
• Extensions can reload extensions (now you can truly build extensions that are self-updating)
• Extensions can talk to each other (this one is so interesting I don't even know what to think yet!)
• The getFunctionsAndVariables command can now be used for varScoping - even script-based CFCs. I'm working on this right now. It's got one small issue (you can't get line numbers), but it seems to work well.
• You can open a view and have it not take focus from the editor
• You can now notice when the active file in the editor is changed
• You can now notice when you switch selected tables in the RDS view
• You can now notice when files are saved
• For RDS, you can now add right-click menus for the top level server, database, and file items

And finally - and this one I think is not mentioned in the docs - your extensions can now work with non-CFM/CFC files. I think that's a big one and it really opens up the possibilities with extensions.