Adobe has published a couple of days ago the new Adobe Exchange at the Adobe labs: http://labs.adobe.com/technologies/exchange/
It is a new way to browse for extensions directly from a panel integrated into Dreamweaver and to acquire and pay for them directly (no need to go to the developer's website or manually download and install the extensions). It's similar in some way to the installation of plugins from WordPress and on the other hand, for the developers, it's something similar to the Apple Marketplace.
A lot of modifications and improvements will be probably applied to the new Adobe Exchange before going out of the Adobe Labs; anyway it's ready to be used for both developers and end users.
Since this will be the main marketplace for Dreamweaver CS6 and later versions we have already prepared all of our extensions to be listed in the new Adobe marketplace and some of them has been already approved & published.
We expect that the new marketplace will simplify the actions required for downloading and installing the extensions into Dreamweaver, avoiding at the same time the problems related to multiple versions of the Extension Manager installed in the same computer. For the developers the current rules aren't very attractive, there are a lot of restrictions in the formatting of the product information and a bit high fees, at least that should keep most of the unuseful/low-quality extensions out of the new Adobe Exchange in order to make it a more reliable marketplace.