A lot is going on with Basilisk Games, the bringers of the Eschalon Books cRPG series.
Basilisk games support their games well and didn’t forget about Book 1; recently they released 1.06 version which is compiled using the latest Ubuntu 10.04 libraries and should work better with newer distributions.
All you have to do to get the latest version is to email Basilisk Games with your purchase information (order number works best!) and they will activate a new download link for you.
But if you have no problems with your current version of Book 1, you don’t need the update as it offers no additional content.