Which text editors take advantage of Lion's Versions feature?

TexShop, the Latex editor, now supports Lion versions. It is not a general Text Editor but can be used as such and supports many of the features you requested.

http://pages.uoregon.edu/koch/texshop/lion.html

Aptana is geared towards web development (html, javascript, css, php, ...) . It's based on Eclipse, which has build-in automatic version history, so I guess Aptana has it too.

Using the version feature (to either replace or compare the current version) is as easy as right-clicking a file (see image)

Pros:

• It's free
• has syntax highlighting, sidebar, auto-indent and many more.
• cross-platform (should you ever switch)

Possible cons:

• Probably not using Lion's versioning
• Not exactly lightweight
• Really targeted for web development, so less of a general text editor.