And it looks very well done:
http://www.magentocommerce.com/
It's still in beta, but there are plenty of good features in it already - and more on the roadmap:
http://www.magentocommerce.com/roadmap
Ubercart suits the project i'm working on, as it's a site with a store on the side, not primarily a store.
Anything that can help kill off OSCommerce is a good thing... 



). They definitely have a fine marketing department, but it's hard for me to imagine their CMS features or extensibility will come close to Drupal's.



a review of note:
Magento is coming
which prompted the response:
Drupal shopping carts: Ubercart and e-Commerce module still the way to go
That roadmap looks pretty ambitious, but there are some neat features there.