2.02.0

• Add a Lua mode.
• Fix reverse-searching for a regexp.
• Empty lines can no longer break highlighting.
• Rework scrolling model (the outer wrapper no longer does the scrolling).
• Solve horizontal jittering on long lines.
• Add runmode.js.
• Immediately re-highlight text when typing.
• Fix problem with 'sticking' horizontal scrollbar.

2.01.0

• Add a Smalltalk mode.
• Add a reStructuredText mode.
• Add a Python mode.
• Add a PL/SQL mode.
• coordsChar now works
• Fix a problem where onCursorActivity interfered with onChange.
• Fix a number of scrolling and mouse-click-position glitches.
• Pass information about the changed lines to onChange.
• Support cmd-up/down on OS X.
• Add triple-click line selection.
• Don't handle shift when changing the selection through the API.
• Support "nocursor" mode for readOnly option.
• Add an onHighlightComplete option.
• Fix the context menu for Firefox.

2.0.0

CodeMirror 2 is a complete rewrite that's faster, smaller, simpler to use, and less dependent on browser quirks. See this and this for more information.