Can cookies cross between browsers?

[American Psycho]

We are well familiar with the tried and true method of using different user accounts to handle the cookies and other browser tracking information between the different internet accounts but there are times when I want to access two accounts within the same user.

Let's say I have eBay account A that I only use with Firefox, and then eBay account B that I only use with Chrome - am I safely protected from these accounts getting linked or is there risk that cookies and other objects will leak and be shared between the different browsers?

[Modee]

This is something that is specifically covered in the Short List. A lot of the questions you are asking are in the Short List.

Also in less detail, here:
PayPal and EBAY cookies - crossing from one browser to the other? - Free EBAY, PayPal, Business and Law Forums - Ebay Suspension, PayPal Limited