Lync 2010 for Windows Phone is now available in the market place !!
You can find it on http://www.windowsphone.com/en-US/apps/9ce93e51-5b35-e011-854c-00237de2db9e
Unfortunately, your Lync Server should be well configured to work with. You can enable it, like described here: http://msunified.net/2011/12/12/enabling-lync-mobility/
Enjoy !