This is great news for all great creatives with amazing videos on Vimeo! It will be interesting to see how the pay-to-view is presented to the buyers and how flexible the solution is. I see there are quite some limitations already for Tipping: no embed, Paypal only, see their FAQs http://vimeo.com/help/faq/tip_jar
It seems many other video or content platforms tried to launch their own pay system, yet often they realize this is not their core business and then look for other best in class components to integrate.
Actually, for those who cannot wait until 2013 to sell videos pay-to-view, Vimeans can try Cleeng. Takes 2 minutes to protect a video:
http://cleeng.com/us/s/sell-online-video choose for Vimeo and you can start selling in minutes