By default Lync 2010 pulls from Outlook's contacts when using "Search" in Lync. I find this feature annoying because we don't use Lync for calls of any kind. We only use Lync for IM and Presence internally. Hence, seeing my Outlook Contacts in Lync is of ZERO use to me. All of my Contacts show up as "Presence Unknown".
example: Tom Smith is a GAL, internal, Lync enabled user. Tom Jones of from my contact list.
Very simple Solution:
On Lync Server (mgt shell)
set-CsClientPolicy -Identity global -ExcludedContactFolders "Contacts"
This will now exclude Outlook Contact from populating Lync searches....great.
Fast Forward, upgrade Office from '07 to 2010.
Lync is now showing contacts again. This time from Outlook's "Suggested Contacts", a new feature of Outlook 2010. Suggested Contacts is a new contact folder starting in Outlook 2010. I find this feature completely useless but that is another topic.
To view the policy:
Get-CsClientPolicy -identity global
Check the settings: