I am using an xml file (code below) to add 4 customized presence states in Lync 2010 (Windows 7 Pro). You can see that availability of online, busy and do-not-disturb are in use, but what about away? When I try to use away in place of the other three, the custom states disappear altogether from the Lync client. It's not liking the term "away".

<?xml version="1.0"?>
<customStates xmlns="http://schemas.microsoft.com/09/2009/communicator/customStates">
  <customState ID="1" availability="online">
    <activity LCID="1033">Working from Home</activity>
  </customState>
  <customState ID="2" availability="busy">
    <activity LCID="1033">In a Live Meeting</activity>
  </customState>
  <customState ID="3" availability="busy">
    <activity LCID="1033">Meeting with Customer</activity>
  </customState>
  <customState ID="4" availability="do-not-disturb">
    <activity LCID="1033">Interviewing</activity>
  </customState>
</customStates>

The availability values are limited to the following strings: Online, Busy, and Do-Not-Disturb.

You can check it at http://blog.schertz.name/2010/11/adding-custom-presence-to-lync/