Managing presence indicators such as Available, Busy, or Away to reflect user availability
Since my original post was to let people know that it's now working for me and I'm not from Microsoft, I cannot tell you why it's not working with the version you have.
The only thing I could think of is that this function was only implemented with the preliminary version. Maybe somebody from Microsoft could confirm this or if the version you have, support the status badge on the TaskBar icon?