First of all thank you for writing Desktop GIS. It is just the kind of book I was looking for and has been very helpful.
One open source desktop application which is curiously missing from the book is MapWindow GIS which can be found at http://www.mapwindow.org/.
I use Quantum GIS to plan and document my geocaching and hiking trips in various nearby Florida parks. The GIS department of local land management government agency makes available on their web site high-quality (as good as 6 inch per pixel!) imagery which is updated every year. This imagery is provided in MrSID format which seems to be fairly common.
Even though MapWindow GIS and QGIS both seem to make use of GDAL, which has the ability to read MrSID format files (at least it does in FWTools 2.2.8), MapWindow v4.6 is able to load SID files while QGIS v0.11 is not.
I don’t appear to be alone in my frustration in QGIS’s lack of support for MrSID format as is evidenced by this tread in the Quantum GIS Forum: http://forum.qgis.org/viewtopic.php?f=5&t=385
Is there some reason why support for this format continues to be left out of QGIS?