WSE 3.0 June CTP is now available !
The first public build of WSE 3.0 is now available on MSDN, The build requires Whidbey beta 2.
Check out what's new in WSE 3.0 over here
Then download the WSE 3.0 CTP Runtime WSE 3.0 CTP Full pkg
And also take a look at the two WSE HOL:
WSE 3.0 Technical Preview Hands-on Lab - Messaging
WSE 3.0 Technical Preview Hands-on Lab - Security