For the impatient and those that just don't want to bother with compiling from source in order to use a newer version of Xastir, there's a user provided binary package that can be installed with only a few mouse clicks.
The binary package for Xastir that is available in the Debian 6 repository is old and lacks key bug fixes as well as online OpenStreetMap support.
Providing a more up to date alternative, the latest user-provided Xastir binary can be downloaded via the link below:
Be sure the gdebi-kde package is installed. Gdebi can be installed using the following commands.
sudo apt-get update sudo apt-get install gdebi-kde
(If gdebi is already installed, the apt-get application will simply report that and not try to install anything)
Once downloaded, installing the Xastir package is as simple as clicking the deb file in the file manager (dolphin).
The package will installed by the GUI installer, gdebi, which will automatically install any required dependencies.