after upgrading to WP 2.6 I found pages (with pretty permalinks) having Tamil (Non-english unicode) characters in URL don't show up in the public view. I checked even the default themes. They could be seen only in the edit view. They show up if you have default WP URL.
The temporary solution to change these Page slugs into some english characters.
The post URLs are working fine.
Hope this bug is fixed soon.