It looks like it should work.
If your pccard is supported by Linux then it should work out of the box. It should be setup as a serial device and you'd treat it like a regular external modem.
There are some limitations and then there are work arounds for those limitations. Unfortunately I am not to knowledgable about this sort of thing.
I found this:
http://samat.org/weblog/20070128-sprint...-mobile-broadband-on-ubuntu-linux.html
Apparently his device used the usbserial driver by default which limited his speeds to 60MB/s (or I am supposing 480Kb/s).
To get faster speeds he patched and recompiled his kernel. Then he showed howto manually edit the ppp scripts to get automated control over the device.
http://samat.org/weblog/20070127-high-s...eless-modems-in-ubuntu-linux-6-10.html
He seems to have taken a kinda convoluted way about it, but each person has their own paticular way of doing things sometimes.
This guy got it working with the usbserial driver with verizon. Treated it just like a normal modem, notice that he had to 'modprobe' the kernel module with proper PCI identifiers to get it to work.
http://kenkinder.com/evdo-pc5740/
So it'll work after a bit of work, usually. If you google around you'll see lots of different examples. Just search for:
Ubuntu evdo
I doubt that all pc cards will work equally well, but I have no idea which companies or which cards to look out for.