It is doable given the following conditions:
XenDesktop with RemoteFX With Lync and the Lync application is virtualized by App-V.
This video from TechED 11 Europe.
http://blogs.microsoft.co.il/blogs/ronenb/archive/2011/03/29/vdi-and-lync.aspx
Announcement on Citrix
http://blogs.citrix.com/2010/11/18/microsoft-lync-office-communicator-on-xendesktop-5/
Press on Right Arrow on the below link
http://hdx.citrix.com/hdx-realtime
Thanks to Hussein and team for providing some of the info