This release contains a bunch of bug fixes to DSL Tools V1.0. It has CTP status right now, but will turn into a released, redistributable new version of DSL Tools early next year with the RTM of the V4.0 SDK.
We're trying very hard to ensure that this release will be redistributable to your end users without you having to ship a new version of your DSL Designers. If you come across anything in testing that breaks an existing designer when you try the December SDK, please let me know as a matter of urgency. Of course, some bugs will only be fixed if you regenerate your code and re-ship, but we want folks to be able to use the new version of the redistributable with confidence.
One note - the opposite of the above isn't supported - a DSL designer built against the new runtime won't work on the old runtime as there are a few new virtual methods on some of the base classes that won't be there.