Isn't it somewhat of a pipe dream? I mean, they can build more secure programs, but I don't believe its possible to build impenetrable code.

The security of any coding is only as good as whatever is known now or what those particular developers used. Its only a matter of time before someone more clever comes along or new technology is created that nullifies that security.

Being Microsoft, they are constantly under a microscope- both because so many dislike them and want to embarass them by finding flaws and because finding a vulnerability in a Microsoft product creates such a target rich environment. I think that under such a microscope someone will eventually find some vulnerability no matter how hard Microsoft tries.

That said, I think that it is nice that they make the effort. While their efforts may not build perfect or impenetrable code, eliminating vulnerabilities, especially the ones that are easiest to exploit, will still significantly improve things.

Just like I can leave my house unlocked- that is one level of security. I can lock the door- that is another level. I can lock the windows. Install a deadbolt. Install an alarm system and video surveillance. In the end my house won't be impenetrable, but each increased level of security keeps out another level of burglar so that only a dedicated professional should be able to get into my house.

Similarly, I would hope that Microsoft's efforts will make strides toward building software secure enough that only a dedicated professional hacker can break it and not just your everyday script-kiddie.