Bryan, Matt, David et al,

I heartily agree with Matt's comments about ease of use being essential. David and I are both involved offline in a project around Traxian's offering, which I'd described to him as "Skype for B2B" (not that we'll be trademarking that, obviously <g>). Traxian is a lightweight, uniform client for integrating B2B seamlessly with popular applications like QuickBooks - and which leverages hosted services to handle the variability in different partner connections (i.e. format/protocol translation, data aligment etc).

As some real-world background... our first product was a (fairly) pure client-to-client model. Worked well in the lab... but in practice the amount of tweaking and updating required on the client for each end-to-end use case led to poor customer experiences and poor supportability. Pure P2P implementations here can work fine "out-of-the-box" where requirements and interfaces are well-defined and stable - but we're a long way from that in the real world, especially when SMB application integration (vs just file delivery) is a requirement. Approaches that start with message delivery, and see app integration as a "plug-in" will not work, in my view.

To your original question Bryan: the key requirement, I'd suggest, is seamless end-to-end integration. Any technologies or standards that relate to internal/B2B connections are fairly irrelevant from a user's perspective, though they may matter for other reasons.

Regards, Roger