MODULE_CURL is deprecated as of v6.1 - You can find the new docs here!
The NETCURL module is a package with network handling routines and "smart" network communication libraries. By means, the module find available drivers on the platform it resides, and communicates with a "best practice". No pre-setup is required like many other libraries - netcurl always returns prepared data from the source that it is requesting data from.
Version 6.0 can be found here.