A while ago I wrote briefly on why the Singularity might not be near and my estimates badly off. I saw it linked the other day, and realized that pessimism seemed to be trendy lately, which meant I ought to work on why one might be optimistic instead: http://www.gwern.net/Mistakes#counter-point
(Summary: long-sought AI goals have been recently achieved, global economic growth & political stability continues, and some resource crunches have turned into surpluses - all contrary to long-standing pessimistic forecasts.)
No, not particularly that I can think of. The only examples where people stop working on optimizing a problem is when the problem has become so easy that it simply doesn't matter to optimize further, but such examples are rare, and even in those sorts, further optimization does occur just at a slower place.