WordPress Plugin Repository
The idea behind this repository is to provide a rich environment for developers to create and share their work on WordPress-related plugin development. The WordPress plugins repository is a high-availability set of development tools -- a wiki, version control using Subversion, and bug tracker -- that aims to nurture the active WordPress development community. WP-Plugins.org is completely free to use.
All files and content here are licensed under the GPL unless otherwise noted in the source.
All the action is now on the extend section of WordPress.org:
You can apply to be hosted there:
Read about using Subversion:
Read the FAQ:
And finally a sample readme file: