Tennovan, fwiw, I rarely close my browser (and have some times gone as many as 8 days >gasp< without rebooting windows)... so that may have a bearing on my observations of the cart retention.
I know what you mean. I'm a programmer/web developer and will sometimes go WEEKS without rebooting my system... though I do logout pretty much every night. My problem is that throughout the course of a workday, I'll open and close 5 different browsers while testing sites. Oh well, I'll just try to be more disciplined and use the wish list instead.