I was playing with Web Parts connections and came across a beautiful sample/tutorial by Carlos Aguilar Mares

http://www.carlosag.net/Articles/WebParts/connectionsTutorial.aspx

Looks Carlos wrote it with the Feb CTP or Beta 1 as the asp:Connection  object was renamed to asp:WebPartConnection  in Beta2 -so the sample no longer runs as is...

To get his sample to run on Beta2 simply requires changing the following line:

 <asp:Connection ID="SampleConnection" ConsumerID="ConsumerWebPart1" ProviderID="ProviderWebPart1" />
 

to the following:

    

<asp:WebPartConnection ID="SampleConnection" ConsumerID="ConsumerWebPart1" ProviderID="ProviderWebPart1" />