Opening/saving formats
Import

• Import of audio from QuickTime (mov, aac, m4a) files now supported on OS X.
• Broadcast Wave Format (BWF) wave files can now be imported.

Export

• Metadata can be added to OGG files.
• Improved Export option selection.
• Additional export options added to MP3 and FLAC file formats.
• Command line exporter now supported on Windows and OS X.

Effects

• EQ effect
• Responsiveness improved.
• Several enhancements added.
• Batch support added.
• New Auto Duck effect
• Added previewing to AudioUnit effects.
• Much improved Noise Removal effect
• Effects previewing can now be canceled.
• New DTMF Tone Generator effect
• Additional options available in Noise effect.
• Improved the Tone Generation effects.

Other features

• New built-in screen capture utility
• Major speed improvement in Spectrogram rendering
• Increased support for drag and drop on OS X.
• Support added for building against wxWidgets 2.8.x.
• Can now open multiple Audacity Projects at once from Explorer on Windows.
• Improved main window sliders.
• New support for snapping while selecting and sliding
• Improved track focus handling and visual feedback.
• Speed improvements and handling of resizing/zooming in tracks
• Spectrum view can now be zoomed.
• New internal file cache to improve handling of project files over networks

Also

• Many improvements to language specific translations
• Numerous stability improvements