Actually even before MS posted the patch in early July there was clear evidence that mischief would occur in the near future back in March: anyone watching their public facing networks would have seen a marked increase in scans on these particular MS ports: 135 - 139, 445 etc.
The best advice is to have a monitoring system that you actually check or that alerts you to increased activity in a certain area. This way you know the exploits people are attempting: once your public facing systems are locked down it is very difficult for an intruder to comprimise your systems.
If you are concerned about snooping there are numerous free sites on the internet run by government or academia that offer useful information: one of them is cert.org which you can check for after the fact notices of particular internet - wide problems.