Yes, H4 (as opposed to BCSP) versions of the cards will work with the Linux stacks.
When inserted into Linux, our Bluetooth cards identify themselves to the OS as a serial port. This makes it very easy to talk to the cards at the HCI layer over the virtual serial port. We have supplied PCMCIA cards to companies that are now successfully running them in Linux using the Axis stack and the IBM Blue Drekkar stack.
For more details see: http://medien.informatik.uni-ulm.de/~frank/bluetooth/bluetooth-howto.html
(Not supported by Brainboxes)
We are also happy to supply interface information which will allow you to access the card directly at the HCI layer. We are currently supplying hardware only development kits directly from Brainboxes.