No, John... Another myth remains!!!
I had the same problem(cart button not functioning on safari)
Several days later, now I have same problem but on: Firefox.
Website in question:
http://www.onecco.netVersions: Joomla 1.5.12 & Virtuemart 1.1.3
The last thing I remember doing is, adding advertising ads(above search & below featured products scroller) Of course, I removed the ads, and still the same.