Cross Multi Site/Store Shopping

Does anyone know of a module that lets you hold your shopping cart across different multi-sites/store.

We have 3 different shops all running off of the same code in the same director. Wwe dont want each of the shops to show each others products, but if they add products from one shop, and move to another through a link on the side bar, that shoe card and contents will transfer.

Cheers,


Out2lunch

i also have the same concern... is there any available plugin/mods that will consider cart content of each store independently?