Arguably, app.net provides only marginal value in its current state. It never developed into the "global authentication" platform that it really promised to be,

Arguably, app.net provides only marginal value in its current state. It never developed into the "global authentication" platform that it really promised to be, and who's going to pay for a less-popular Twitter? If app.net provided the same level of utility that delicious does, I doubt very much that they would be in the same financial straits that they are now.