Just wanted to let everyone know, before they upgraded, that Kontakt 4 does not currently support sound sets.  Hopefully they'll get this worked out soon, because the interface improvements made from K3 to K4 are pretty awesome. You finally have the ability to resize the Kontakt window, like other windows - rather than picking one of three sizes which [i]can[/i] be customized).

Here's the ";official"; word from Daniel Spreadbury, the product manager of Sibelius:

Second post in the following thread.
http://www.sibelius.com/cgi-bin/helpcenter/chat/chat.pl?com=thread&start=473412&groupid=3&&guest=1

Thanks for the heads up Bryan.

Blast why do i always find these threads [i]after[/i] i upgrade!

Do we have any update on this issue? I still can't see the sound sets in the list. What's weird is i get all of the MIDI soundsets to display!

See this post. 

https://www.tapspace.com/forums/index.php?topic=3607.msg19062#msg19062

If you're using Sibelius 6, you just need to update to 6.2.