In order to release a new version of the plugin to wordpress.org, perform the following steps:

1. Update the version in tiny-compress-images.php
2. Change the 'Stable tag' in readme.txt to the new release number.
3. Add release notes to readme.txt.
4. If you've changed the plugin to work with newer version of WordPress add that to the readme.txt as well.
5. Commit and push to GitHub.
6. Create a new release in GitHub and pull it in.
7. Locally, checkout the new tag: `git checkout <tagged version>`.
8. If not already done so, checkout the plugin's Subversion repository: `svn co http://plugins.svn.wordpress.org/tiny-compress-images`.
9. Run `svn update` when the Subversion repository already existed.
10. Update svn:ignore property of trunk when .gitignore is updated: `svn propedit svn:ignore trunk`.
11. Delete everything in trunk `rm -rf <path-to-local-svn-repo/trunk/*`.
12. Manually copy the Git release to the local Subversion repo: `git ls-files | xargs tar c | tar x -C <path-to-local-svn-repo>/trunk/`.
13. Add new files `svn st | awk '/^\?/ { print $2; }' | xargs svn add`.
14. Delete deleted files: `svn st | awk '/^!/ { print $2; }' | xargs svn rm`.
15. Commit the trunk to Subversion: `svn ci -m "<message>"`.
16. Tag the new release in Subversion and commit: `svn cp trunk tags/<version> && svn ci -m "<message>"`.