The full guide is here…

http://www.microsoft.com/en-us/download/confirmation.aspx?id=39071

For those of that already have PIC enabled (most of you i would assume)…. i found the guide to be a little bit off, in that my existing provider was called “MSN” – not “Messenger”

So, my suggestion is to open up your Lync powershell and…….

Get-CsPublicProvider

note the name of your msn/messenger federation partner (it will likely be “messenger” or “MSN”)

Remove-CsPublicProvider -Identity MSN (or messenger, depending on step above)

New-CsPublicProvider -Identity Skype -ProxyFqdn federation.messenger.msn.com -IconUrl “https://images.edge.messenger.live.com/Messenger_16x16.png” -VerificationLevel 2 -Enabled 1

Restart your lync client and check that Add Contact | Add contact not in my organision | Skype exists

now enjoy IM and audio calls between Lync and Skype…. video apparently coming soon.