some very good points in this thread, here is my two cents worth....
abs does NOT work if light is on.
ecu is different part number for tracs and non-tracs.
ecu can be repaired and this is usually most cost effective repair.
to my knowledge the new ecu is the same part number as the older units, i dont think it has been changed.
nearly all later 850,s70,old v70s have this problem with the integrated ecu/abs pump unit.
although these abs units are on volvo cars they are not made by volvo.
true volvo has not done a recall for this part why? well it depends on how you look at the problem,every part on a car has a service life that it is expected to last for. most of the cars with this problem are 6+ years old now, how do you know that these abs ecus are supposed to last longer than this? i know it sounds weird but there are so many variable reasons why a computer based unit may fail that volvo wouldnt issue a recall as the new units could fail as well if the cause of failure is on the car and cant easily be diagnosed or repaired.
i personally aggree with you that they do fail too soon and shouldnt but i cant see volvo coming to the party on this one,go with the repair option. also people looking at buying one of the above mentioned cars should take this problem into account and allow for it.

steve.