Comment from my point of view... (Score 1) 499
I work on a web based application/service that allows small to medium size companies in our industry to offer the same sort of experience for their customers that a much larger company would offer. As part of this system, we offer the ability for our clients to incorporate third party applications into our product using various single sign on methodologies.
Unfortunately, many of these scenarios require third party cookies to be allowed in order to maintain two different sessions in two different applications (from different sources). We already struggle with this in the browsers that already have 3rd party cookies disallowed by default. If Firefox goes through with this, we anticipate huge numbers of unhappy end users whose experience will be very negative until we are able to educate them on how to allow 3rd party cookies.
I hate ad spam as much as anybody, and use all the blockers and no-[whatever] add-ons, and ghostery, and, and and myself. But I'd sure like a solution that doesn't involve breaking perfectly benign features as well.