AFAIK, there's still no ThinPrint or Location Based Printer support for 2008R2 as a desktop.
You will need to purchase the full-fledged ThinPrint product to get the equivalent functionality for 2008R2 desktops.
Does anyone know if this issue has been addressed in the forthcoming Horizon 6?
...or with Horizon DaaS for that matter?
Yes, we have plan to support it in future release.
Helen - can you please clarify if you mean Horizon 6 or some future release after?
Not in Horizon 6, but in future release.