I know this has been covered but I can't help but notice that my bookmarks show "snapshots" of visited web pages, basically a screenshot, so obviously the system is capable of it.... Why not just make it a feature??
It will be a feature in ICS and you can do it on your DINC if you are rooted and use a third party app like Shoot Me. I think Samsung has a screenshot feature on it current phones. The feature is simple enough to include, it just has not been native to Android up to this point and HTC chose not to add the feature to Sense.