This is a continuation of my previous blog post on my initial testing experience with Lync 2010.
I actually discovered that I need to rename the Lync gateway. I was initially named 1:1 so I renamed it to Lync2010. I also needed to run the ExchUCUtil.ps twice. The first time, the Lync server didn't get associated with any dialplans. I reran it and it was associated with the dial plan.
UM worked for the upgraded users after running this step.