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. Commit and push to GitHub.
4. Create a new release in GitHub and pull it in.
5. Locally, checkout the new tag: `git checkout <tagged version>`.
6. If not already done so, checkout the plugin's Subversion repository: `svn co http://plugins.svn.wordpress.org/tiny-compress-images`.
7. Manually copy the Git release to the local Subversion repo: `cp -R . <path-to-local-svn-repo>/trunk/`.
8. Commit the trunk to Subversion: `svn add trunk/* && svn ci -m "<message>".
9. Tag the new release in Subversion and commit: `svn cp trunk tags/<version> && svn ci -m "<message>"`.