LawFont.com has said it well:
It really does seem quite remarkable that — assuming the Men at Work song does reproduce the melody of "Kookaburra" — it took 27 years for anyone to notice. The Men at Work song was composed and published in Australia in 1981 (when, of course, Sinclair was still alive). It is a matter of public notice that the song was immensely successful all over the world. That was 3 years before Sinclair’s autobiography and 6 years before she made the assignment of copyright to the State Library upon which the applicant’s title to sue was said to be founded. The action was only instituted in 2008.
LawFont also makes some very interesting points about copyright length and the difficulty of proving the copyright of this song when all the various witnesses are dead.
My biggest problem with current Copyright isn't so much the length of it (although I do believe it is generally too long, especially in the US) but how badly it is documented, and how difficult it can be to properly gain permission to use a copyrighted item.
Further, the use of copyright to remove the right to copy ever (deleted CDs, claiming copyright to prevent the publication of facts).
If you want to use a copyrighted item who do you talk to? How much does it cost? Who owns the copyright? If copyright is to be as long as it is, these things should be well documented and simple.
But this case doesn't have much to do these problems, they've just been nicely exampled from it's publicity. This case surrounds the age old sampling problem we've had in music since the 80s.
How much is your piddly little 10 second riff worth to the overall composition of a song?