joyent/node — comment on commit 5b8e1dabbc117b38c56f874f4e6d5b7e537cd3c1
File:  line 0
By isaacs:

They're capitalized because they're class names intended to be called with `new`.

If you prefer to use the older lib, you can package it with your application and refer to it via a relative path.

I tried really hard to find a name that wouldn't collide, but zlib, z, compress, deflate, and gzip were all taken, and "zlib" really is the best name for what it is, since it's a pretty direct binding to the functionality that zlib provides.