the bottleneck is most definitely in the ISP service if you are talking about an NIC for use with a broadband connection. as it is 100MBPS really wouldn't even be a problem.
edit: after reading some of the things on the site i definitely think it's a rip off. sure some of the technologies they mention have potential but because they are so overpriced i don't think the potential will be realised through them. the concept of a network dedicated processor unit is quite smart. think of all networking activity and protocols being offloaded to an NIC rather than CPU then only a visual frontend is required for things e.g. DC++ and other file sharing utilities. i think this would certainly make sharing, leeching and gaming at LAN parties more enjoyable if it becomes main stream
. just to re-iterate, technologies like this tend to never take off if they remain proprietary but if they become industry standard we'll be buying them for $20 in a year or so