Over the last year or so, I've received a couple of reports from parents (much appreciated too) of escape paths that led to someplace outside the included web sites, eventually to a search engine and failed to block search engine access.
It has always involved an intricate path, many clicks and it seems, footer links.

Anyway, I need to nip this in the bud once and for all :p

So... I've added an extra safety net that explicitly blocks any and all attempts to access certain sites.
Here is the shortlist for the v1.5 release:

google.com
yahoo.com
msn.com
live.com
ask.com
myspace.com

At least in my testing so far, its working exactly as planned and has been 100% effective.
Its not really an area for 99.9% effectiveness rates. ;)