Had a scare yesterday. Upgraded the webcalendar script we use for the school's networked and online diary, only to find all the entries had been put back by 5 hours. For a worrying while it looked as if it was a live-with-it-or-ditch-it PHP version error, but luckily there was a workround. Phew!
This is just one of several problems I've encountered with open-source upgrades recently. We can't run the latest version of Moodle because it's incompatible with the PHP brew our remote host is running, and our MovableType blogbook was out of action for the entire autumn because I had to backtrack to an older version for a similar reason. Undoing mysql database upgrades and repopulating tables from sql textfiles is not a restful exercise, especially when you have to grab opportunites to do this in the midst of busy school days.
Have been reading the reaction to the pre-Christmas announcement of Becta-approved learning platform packages with interest. It doesn't appear at the moment as if the list carries much credibility. Certainly a number of people have gone on record as saying that they will carry on with open-source solutions regardless.