Are there any external Hard Drives with Thunderport yet ?

During the CES avalanche of press releases and "new" products, both Seagate and Western Digital annoucned them. In the case of Segate and their GoFlex models, they are designed around separate connectors. Once you have the drive, you buy whatever connector you want, including the Thunder one.

I didn't see any laptops that have an port for them and know nothing about Apple computers. Are you sure you Mac has one?

Apple was first to market with Thunderbolt about a year ago, since they partnered with Intel to develop the interface. I believe the new wave of PCs that Intel have branded Ultrabooks, and that are the Windows equivalents to the Macbook Air, are the first non-Apple computers to feature thunderbolt. Ultrabooks from various PC manufacturers started to appear during Q4 2001.

Will a future add-in card be Thunderport supported?

I haven't seen any add-in card products yet, but that does not mean there aren't any. Since Thunderbolt carries both video and PCI Express (the connector is identical to mini displayport), I guess an add-in card would also have to be a graphics card. It seems portable computers are the first to have Thunderbolt ports. My guess is that desktop motherboards with integrated graphics will be next, and then discrete graphics cards.

For now, the primary use is convenient docking of portable computers (video, network, and storage all in one cable). Apple has a Thunderbolt monitor that serves as a hub. Just plug a thunderbolt cable between your mac and the monitor, and then connect your ethernet and usb drives to the monitor.

Next comes external graphics cards as a way of upgrading the graphics for portable computers and low-end desktops. MSI showed this product at CES:

http://pcper.com/news/Graphics-Cards...Upgrade-System

I'm not sure Thunderbolt for storage will be big hit. We already have e-SATA, USB 2 and USB 3 for this, and they are simpler interfaces that are cheaper and easier to implement in an external hard drive, not to mention in the computer.