Magento cookie bug with WebKit based browsers

Don't develop using localhost as your domain name. I typically use apache to setup a fake custom site at a domain like magento.dev, and then add

127.0.0.1    magento.dev

to my hosts file. Beyond working around the cookie problem, this also lets me have an infinite number of sites running locally.

Is your server time and computer time correct? This causes the majority of cookie issues with Webkit based browsers - whereas IE and FF are far more tolerant (ignorant).