Mark Jaquith

Redirect Old Slugs allows you to change your post slugs without breaking your permalinks. People requesting the old link will be redirected to the new link. This all happens automatically.
Note that this functionality was brought into WordPress core for version 2.1, so this plugin is not needed. When you upgrade to WordPress version 2.1 or higher, your old slugs will be kept and will keep on being redirected without the need for this plugin.

Redirect Old Slugs

Allows you to change your post slugs without breaking your permalinks.

pbosakov

This plugin will automatically transliterate permalink URLs when you save a new page or post with a title in the Cyrillic script. 
Romanization presets are available for all the major languages using the Cyrillic script: Russian, Ukrainian, Kazakh, Belarussian, Serbian, Tajik, Bulgarian, Kyrgyz, Bosnian, Mongolian, and Macedonian. 
The plugin can also romanize permalinks for any pre-existing posts, categories, products or other items with a title written in Cyrillic. 
Only UTF-8 encoding is supported.

Cyrillic Permalinks

Automatically transliterates Cyrillic letters in permalinks to their Latin phonetic equivalent. Multi-language. Can convert pre-existing permalinks.

Redirect Old Slugs vs Cyrillic Permalinks