Having just performed the usual 'aptitude update' and 'aptitude full-upgrade' on all my (13) Pi's, I found that Apache2 (2.4.7) was reconfigured (without my permission) so in effect, the web pages were dead. This also affected wget which I use on remote machines to grab some data updates.
I couldn't find much about the problem but it seems that '/etc/apache2/sites-available/000-default.conf' was rewritten with a new default configuration. This is symbolically linked to '/etc/apache2/sites-enabled/000-default.conf' Fortunately I had an old version on a Sheevaplug and I used that configuration to edit the Pi's file. After a 'service apache2 restart' all was well and normal service was resumed. However I have unecessarily lost 24 hours of data and in a near future scenario, could have affected my home environment.
I note the same problem on one of my Sheevaplugs but the other two are fine. Not sure about Guruplugs, Tonidoplugs and Cubox's yet.
I can now confirm that my Sheevaplugs, Cubox's, Guruplugs and Tonidoplugs were similarly afflicted by the unwarned Apache configuration changes.