This is a port of Footnotes 6.x-2.5 to Drupal 7 (hence, 7.x-2.5). There are no new features other than the Drupal 7 compatibility.
Looking for new maintainer!
With this release I'm announcing my intent to step down as maintainer for this module. Footnotes was first released in June 2006 and today, 4 Drupal major versions later has over 1100 websites using it. If you are interested to maintain this module, please be in touch and I'll help you. See the project page for details.
Removed features and known issues
The Footnotes Views API added in 6.x-2.5 is not yet ported to Drupal 7, as the Views module itself lacks a stable 7.x-* version.
The Textile variant of Footnotes was removed, it has been deprecated and unmaintained for some years now. You can use the normal Footnotes filter even if you are a Textile user.
Better URL filter is removed since the standard URL filter in Drupal 7 core includes that code. (Yay!)
Footnotes TinyMCE plugin is removed, use the Footnotes Wysiwyg plugin instead, it contains a TinyMCE plugin.
The CKEditor plugin works with CKEditor 3.3.1 but apparently some newer versions only partially work, see the README for details. (This is unrelated to using Drupal 7, something is changed or broken in CKEditor.)