Hi. The latest release is v3.1 and the difference between the standard PA (Private Assembly) and Enterprise edition is that the standard edition does not include source code and also includes the license to install the module on only one DNN installation.
DNN stands for DotNetNuke and is a free open source portal framework that you can download and install from http://www.dotnetnuke.com
Sharepoint (also known as WSS 3.0 and MOSS 2007) is a Microsoft Portal product in which you can add 'web parts' to your portal such as the Flash Image Rotator web part that we have. In DotNetNuke the term is 'modules' and for Sharepoint the term is 'web parts'.
I personally recommend DotNetNuke over Sharepoint as I believe its much more customizable (not to mention free) but for some implementations Sharepoint is better.
Flash Image Rotator is available both as a DotNetNuke Module and also as a Sharepoint / MOSS 2007 Web Part.
The product can also be used/implemented as a stand alone product without either system but the configuration settings has to be manually edited in an XML file on your server (in other words you can use the Flash Image Rotator with a standard HTML web site but more work is needed since there is not a user interface for editing the settings of the rotator).
Hope this helps!
-Chad