http://news.com.com/Sony+cracks+down...3-5885945.html
Running unauthorized code will void your warranty. Sony constantly update their firmware version to close up these cracks and actively try to get everyone to upgrade by insisting new games require the updates- plus that and they havn't release a UMD burner so they do care.
P.S. I know nothing about hacking and have no interest in learning, so I don't know anything about the memory stick boot.