This sounds great to me, because you can even use it right where you are:
http://smithsonianscience.org/2011/05/new-mobile-app-that-identifies-plants-by-leaf-shape-launched-by-smithsonian-and-columbia-and-maryland-universities/
here is a download for iphone and ipad: http://leafsnap.com/ did not find out for android yet..
it is an app, I never used it so far, but I knew a german website, which has the possibility to identify plants via images, I just could not figure out, from which country you are, so I looked for something in english and found this.
This is a wonderful plant identifier, I just found it: http://www.shootgardening.co.uk/plant/identify
Anne Rose