Address Book and iCal have gone all naff, like on the iPad, with faux leather. Yuk.
Untested and strictly at your own risk... (straight from a google search)
Code:
http://macnix.********.com/2011/07/change-mac-os-x-107-lion-ical-skin-to.html
grr... I hate PPRune..... replace the stars with *b*l*o*g*s*p*o*t* (without the stars, obviously !)