The problem was originally fixed for all PW4000 powered 767s. A locking device called a Sink-Lock was installed. This pin is supposed to prevent deployment of the reverser, however more recently tests have shown that the pin may not be completely sufficent to stop a reverser. PW, GE, RR and Boeing have all been looking into ways to prevent inflight deployment, with the FAA it is likely that more changes may be made in the future.
All analysis also suggests that this problem could occur with GE engines and RR as well, however steps were taken to learn from the PW problem. But, remember Boing contracted the design of the reverser not PW.
Anyway the problems should have all been fixed as a previous poster stated. The problem does not apply to the 757 as it uses the PW2000 engine and a different reverser set up.