In addition, are you going to trust some cryptographic process for which you don't know the algorithm or implementation? If you are, you're a sucker.
I agree if you mean it is used to secure confidential account information; ie passwords, which are used over a network. I don't mind if an application is password protected and stores it's password garbled with it's own algorithm.
When I started using linux, there wasn't a shadow file. Encrypted password hashes were clearly visible in the password file.The machine was connected to a corporate network. When more people started using the machine(+/- 50 accounts) I started worrying. I knew some people liked the challenge to beat the security of this thing, so I thought I should beat them at their own game. I modified the crypt function to substract one from the salt and modified the password file. It took about 3 months before one of my collueges noticed. He found out by encrypting his own password, which resulted, as expected, in different results. I think it is still in use for .htacces files on one my friends webservers. This shows just one advantage of using open source software.

I think that the security of the system also relies on the implementation taken. I know that there are probably very little people wich could break into a mainframe running MVS, which results in only the few most obvious security holes found. This can be evaluated in 2 contexts :
1 - the system is very secure. There are probably about 100 men who have the knowledge to get to the system that far
2 - The system is very insecure. The biggest security holes are still unexplored. Any mayor hacker could get in.
Personally I'm not sure which one of the above is true. It's a fact that there has been an explosive grow in security reports lately, but I can also remember the security exploits for novell 3/Solaris/. . Back then it was information that was only available to a small group of people, but now everyone's informed there's a mayor problem coming our way if you don't patch your system regularly.

BTW the guy sitting behind me at work is the IT-security officer. We've had some good fun snooping wireless keyboards.