Pretty simple really. If you want the latest update of browscap.ini file, then get it here.
You only need this file if you are running Microsoft's Internet Information Server, and want to be able to detect the different versions of browsers that are floating around out there. Most especially, you'd like an updated version. One that knows about version 6 browsers (Netscape and IE) and beyond...
The current plan is for me to keep updating it whenever possible. But if someone has a contribution, you are more than welcome to help out. Pop along to the browscap.ini summary page if you are interested.
If you'd like the semi-official browscap.ini, it is available at Cyscape. You could download the same file here, without having to go through all that registration garbage. But honestly, why bother? This particular file was the one that Cyscape were serving on the 23rd of April 2002. It was last updated 30th of June 1999. To be fair to them, they have a far superior product in the form of BrowserHawk. Unfortunately this means that it is not in their interest to give you an up-to-date version of Browscap.ini.
This site is public domain along with any work produced.
And a big thanks to SourceForge.Net for the hosting.