One can't forget the London Stock Exchange clusterfuck, but then again that was three years ago.
Given the number of teams that have succeeded with .Net, I'd say that organisational failings are to blame for this one. Have you already forgotten the reputation of the consultants hired to implement it?
Currently, I think it failed thanks to the usual quality of outsourced projects with off-shoring developers than tooling.
Of course it is always easier to blame the tools.