I am exoerinecing this problem with a clients site at the moment using wp-ecommerce 3.7.8 which is going to shift into Market Press!
But I would like to know how Market press handles these scenarios
1. user adds product, but then goes elsewhere without emptyting their cart first
2. user adds item to cart, then removes that item
It appears that in WP ecommerce there is supposed to be psudo cron job that clears out claimed stock every hour and relasese it back into stock - but guess what it doesn't work - what a surprise.
In the above scenarios there was stock in stock, but because the system claimed these items they were showing as out of stock when a user attempted to add them into there cart.
Solution so far is manually editing the values in the DB for every item - yuk!
One other request while I am here, has anyone given any thought to providing a feed for what was google base?