At first I thought, "Wow! Cool. Skype is following the Firefox plugin model, which enables end users to add their own cool little features." Plugins are one reason why Firefox is so popular - due to the developer community it helped to spawn and develop.
But with further investigation I learned that the plugins feature is simply a tab within the Skype 3.0 application that will list several popular Skype third-party add-ons. Then you can simply select the ones you want and it will be a 1-click installation using a standard MSI, .exe or whatever other installer works on your operating system. I suppose bringing the best plugins into a tab within Skype is a good idea. It will expose casual Skypers to some of the best third-party Skype applications.
In other words, Skype 3.0 beta? Ho hum, nothing to see here... Move along...