To be honest, i actually don't care if yahoo tracks me on yahoo properties - in fact, i expect them to. What i DO NOT want is for them to track me across the entire internet through injected javascript, iframes and dedicated tracking domains that serve same-origin analytic scripts from hundreds of sites - that is unethical.
Currently using adblock plus, noscript and ghostery on my FF setup with specific additional controls in ABE for Twitter and FB domains.
it's also a very useful feature of the internet, that browser's like safari 6 have broken. there are other uses to third party cookies besides tracking - a/b testing. many web properties are shared between multiple top level domains. ecommerce sites will do this for example to sell different product lines, but they might want to have similar user preferences shared between the top level domains... you can't do that if you kill third party cookies... or block the same features that we'd use in ad networks to track you... IE10 isn't so bad it's just saying don't do this... so - we'll happily ignore it. safari 6 is the real story that hasn't gotten enough attention in comparison... thankful it's not as widely used or is it... iphone,ipad...
Currently using adblock plus, noscript and ghostery on my FF setup with specific additional controls in ABE for Twitter and FB domains.