As far as title tags etc to describe what a page is about, I think these are still useful and google will still be looking at these for a long time to come. Things like keyword density seem to be less and less important as time goes by, though
However, I think the algorithms will get better and better at picking up on spam and many of the other techniques that the blackhatters use. I’ve noticed far fewer utter spam pages getting to the top of the rankings, although there are still many poor quality banner pages out there getting to the top, with very little content. That may be changing too.
I was reading one of the google patents on ‘scoring traffic associated with a document’ and it seems they certainly go to great lengths to detect spam. Now, that was written in November 2006, so it will be very interesting to compare it to any more patents they produce on the subject.