It occurred to me that Jeremy C. Reed wrote in gmane.os.netbsd.general:
> On Sat, 2 Jul 2005, Zafer Aydogan wrote:
>
>> Software packages are installed into their own separate directories,
>> complete with libraries and all. The goal is to have installed programs be
>> entirely self contained, so that if the lib's on the system change, the
>> package will be unaffected. Each package is installed into its own
>> subdirectory under "/usr/local/MyPrograms/". The PC-BSD installer takes care
>> of making links, setting up binaries to find their required libraries,
>> creating icons, etc. Removing the app is also managed by PC-BSD. The
>> directory is simply removed, along with any relevant icons / links created."
>
> pkgsrc already does same, but as far as I know it (pkgsrc pkgviews) is not 
> well used yet.

From the above quote, it seems that pcbsd is going a lot further than pkgviews.
If a package needs a certain set of libraries, they are copied *into* the
depot of the package - making each and every package self-contained. On
the plus side, this means not having to deal with dependencies.

Ofcourse, this is just asking for problems. I wouldn't want to deal with a
system which has different versions of certain libraries installed, and
with no idea exactly which package is using what version. Because even if
version 1.4.19 of libfoo has been uninstalled, it might still be present
lurking about in a depot directory.

Nasty, nasty, nasty. This is just asking for being bit by security leaks
in unpatched libraries. And having glibc, libpng or any other frequently used
library installed tens or hundreds of times doesn't sound like the epitaph
of efficiency to me.