the website is a bit vague but as you said, the cards
look specific and
seem to be focussed on packet tracing more than typical security
I'm guessing traffic shaping and ... Dare I say it .. an internet that
offers different service to different packets ( saves clogging the
telecom tubes with voip traffic)
Not really traffic shaping. They are intended to be traffic monitors,
rather than manipulators. While you could use them for shaping traffic,
it would involve the cards being able to transmit data themselves, and
unless that's changed recently they don't actually do that.
The easy distinction is: they aren't network cards. They might look like
them, but they don't have a MAC address, and you cannot use them as a
NIC. This may have changed recently, but it's beyond the original
intention of the card as far as I know.
I guess I am interested in what they would be used for
needing the hardware myself. Its pretty top level
WAND, and probably most other people using them, use them for highly
accurate passive captures of network traffic. They have a GPS
synchronised clock, and they insert nano-second resolution timestamps in
hardware. Because it's done in hardware they aren't affected by system
loading. Using something like tcpdump will give less accurate results
pcap timestamp is only microseconds, and if the host happens to be busy
doing other things (like writing a file to disk, or processing another
packet on another interface) it'll delay the timestamp.
You could use them for Snort and so on, but it's only really worth it if
you want nanosecond timestamping or if you think loading might get high
enough that a normal card will have problems dealing with it.