I know the sticky link on the latest firmware (1.29) has some details (see below). Not sure if there is a similar place for older firmware updates.
Release notes for Sansa Clip Version 1.01.29
This new firmware has various bug fixes, including key fixes listed below, as well as enhancements. Upon completion of the firmware upgrade, the device will turn off. Power on the device to complete the upgrade process. If the device does not initiate or complete, press & hold the Power switch for 6 seconds to reset the device and then release and press again to restart.
· Rhapsody licenses expire early.
· Battery indicator is not linear with respect to the play time remaining.
Fast Forward / Rewind Long MP3
· Device will skip to next song if fast forward past halfway through a long vbr mp3 file.
Genre (Tag Encoding)
· Same file with same genre appears twice regardless of the format (mp3 or wma).
· Device does not return to FM tuner display after scanning for stations. Custom EQ Settings
· Custom EQ settings get cleared after power cycle. Miscellaneous
Deleting files on the device is not stable.
- Device highlights “Play Previous” after returning to Music from FM playback
- Increased Brightness for 4 GB devices for better reading under the sun.
- Added OGG-Vorbis (\*.ogg) Decoder Support in MTP and MSC mode:
• Note: PC with WMP10 will not be able to drag and drop OGG files to device under MTP mode
• Workaround: Install WMP11 to PC or use MSC mode instead.
- Audiobooks and Podcasts sorting and resume features:
• Content placed in Audiobook or Podcast Folders are now accessed separately from Music.
• Content with Genre tags of "Audiobook" or "Podcast" are now handled from any location and sorted by the UI.
• PodCasts and Audiobooks are now organized by 2 level hierarchies.
• Podcast content is sorted with newest episode first.
• Auto Bookmark: will prompt the user with "Resume?" or "Restart" option when restarted.
- Much better shuffle algorithm to maintain the sequence of up to 2000 songs. User can skip to the previously played songs without reshuffling. Sequence is preserved after power off and on.
- Handle playlists up to 1000 songs. Fixed playlists with large count taking long time to load.
• Note: Playlist limited to 1000 songs only applied to .pla playlist. For .m3u playlist, there is no limitation.
- Battery power percentage is now displayed on the “Settings \> System Info” screen.
- Device auto powers off if the radio is paused / muted.
- Add support for Melon SKT (South Korea Telecom) MusicDRM v1.4 (For Korea market).
- Performs faster, more complete MTP Format operation.