As an Android user (and I dislike Apple for various reasons that have been covered to death here) I must give Apple credit here - they do seem to have done it correctly from the start.
It does seem Android included encryption in 2.3.4 but I was unaware of this: http://www.howtogeek.com/14195...
It seems android does have full device encryption (not enabled by default). It also has an option 'Clear storage' which "Clears credential storage of all contents resets its password"
I'm glad that Android is no longer lacking here.