Hello Brian Solli,
We had originally planned to release a CTP of the RadTreeListView for WPF along with the CTP version that we recently release for Silverlight, however due to some technical difficulties we had to delay the WPF version.
We are currently in a phase of collecting feedback on the Silverlight version as far as features and functionality, when that is complete and our planning for upcoming service packs, betas, and the Q1 2010 release is more solidified I will email you to update you on the plans for this control for the WPF suite.
Sorry for any inconvenience this may have caused.
All the best,
the Telerik team