Adaptive Path started to fizzle out after their essay on AJAX - not that they ever really did anything of substance anyway. The loss of Veen seems to have been important, and with a recent post you can see that they've become removed from the reality of their profession:
"Systemitize innovation processes"
Tantek recently posted about something he was undertaking and implicitly compared it with the work done by Tim Berners-Lee when creating the first web server and browser. And then it is revealed that Tantek's work has been to do with Microformats. I've never heard anyone rave about Microformats really. I understand that they encourage interoperability, but they're not cool - they don't capture the imagination at all. Trying to mould hCard into something cool when it's really just an XML schema... come on, you can give it a snazzy name but it's just dull.
Adaptive Path don't matter because they're abstracting themselves into essays, and Microformats don't matter because... well, come on, read this and tell me that anyone is going to care.