There is lies, statistics and identity management figures.
Are there a quarter billion OpenIDs? That would be the conclusion suggested by an announcement from OpenID website two months ago. How many of those users have actually used the OpenID protocol even once when authenticating anywhere? For that matter what percent even know what an OpenID is? This has been a major problem with any identity system that spans multiple sites. Users at this point have been trained to lower their expectations, and come to terms with islands of disconnected identity: each username/password works on one website only. Any system where users can authenticate to more than one relying party is confronted with the challenge of explaining this to users. (For example: “If you have a Hotmail or Messenger account, then you have a .Net Passport.”)
Does having 50% of desktops with Cardspace bits represent a tipping point for the technology to magically take off? By this logic, passwords ought to have been about as archaic as the vinyl record because nearly 100% of desktops have supported TLS client authentication and smart-cards since 2000. Even if we disregard Firefox and PKCS11 based interface and focus on IE running on Windows only, that is over 80% of all consumer PCs. Why isn’t everyone authenticating with digital certificates as the PKI vendors have prophesied for the past decade?