Duke Nukem Forever (DNF), for which the term "vaporware" was invented, is supposed to be released in May 2011. I'll believe it when I see it. DNF sets the record for longest game development time at 14 years.
I just realised that I'm the author of some vaporware myself, it has been almost 12 years since 2 of my games were announced :

They've been in and out of development (well, mostly out, especially George 2) ever since. DNF's rise from the dead gives makes me wanna finally make these . Anyway, I guess I have two more years before my games break DNF's record.