Stewart: Indeed. Ideally, yes, it would (the dynamic linker). Alas, neither Castle nor ROD have publically stated interest in shared libraries to any degree (who knows, internally, they might be dead keen on the idea), so integration into the OS is going to be limited.
As for the SCL, having it as a Shared Library is of rather limited value to myself and my colleagues, even though it might be of academic interest, since we use Unixlib almost exclusively. In any cae, we simply don't have access to its source.
One thing I failed to mention about Shared libraries is that it's quite possible to have multiple versions loaded - this is mostly useful when testing development or debug versions loaded concurrently without interfering with the operation of other programs using another version.
Variants on this behaviour seen in Linux include overriding of symbols for memory checking (electric fence) or other unusual behaviour (fakeroot).