Since the release of DNN 3.2 and DNN 4.0, I have been testing all of my modules. Everything worked as planned except I was having troubles uploading the Aggregator and Module Rotator module in DNN 4.0. The error I was getting was  ExceptionSystem.ObjectDisposedException: Cannot access a closed file. at System.IO.__Error.FileNotOpen(). The solution that seems to work is to add the requestLengthDiskThreshold attribute to the httpRuntime in web.config.

 requestLengthDiskThreshold="8192" />

Since getting that upload problem worked through, I've been able to test in DNN 4.0 and all of the modules are working fine. If anyone has a problem installing anything, please provide details and post in the forums and we'll see what we can do to help you out.