[alkonaut]

Wouldn't it be quite easy for a link shortener to find the final target url and just point to that instead of pointing to another shortener url? It could even heuristically try to search further if the pointed to url looks like an already shortened one (i.e. it's shorter than a treshold).

[oneeyedpigeon]

I also wondered this, and commented before I read your comment. The shortener can just follow the HTTP status chain until it gets a 200; no need for length heuristics.