Canvas is a cool concept, but the fact that Apple is taking the position that it believes itself to own intellectual property related to canvas is not very cool. Its actions like this, the proprietary, closed setup of the iphone, and the shuttering of think secret is again making me reconsider my ongoing use of apple products. I'm looking towards a debian laptop next, using openvz to run isolated systems, so that I won't muck up my core install while I tinker around.
With regards to Think Secret, I understand how Apple could be upset about the issue of leaking information getting published, but dragging the publisher through the mud to try and get to the source seems like the wrong way to find out the cause of their own problems. It reminds me of the HP scandal where the investigators broke the law to find out who was leaking information. These companies should make use of some basic information theories by disclosing varied information to various parties and tracking where it goes, to discover who is talking and who is not. Publishers of "one time" address lists do something similar - they include a few fake addresses to see if customers try to use the list more than once.