The SlickUpload 4.0 Release Candidate has been posted. You can get it from the download page. The package includes the new version, as well as full samples. The documentation has also been updated to match the SlickUpload 4.0 object model.
The additions and features include the following and are outlined in the SlickUpload 4 announcement.
Location Based Config
Enhanced Error Handling
Built-in Upload Handler
Note: SlickUpload 4.0 will not recognize licenses from previous versions, so it will function in trial mode. SlickUpload 4 licensing and upgrading will be added to the store shortly.