5.1.1: Minor update to support patch 5.1, no real changes yet, RL has been pretty busy
5.0.4: First pass at fixing Favorite/Forbid summon filtering for pets (was totally broken) and Forbid filtering for mounts
5.0.3: A few more small bugfixes (error case for some slash commands)
5.0.2: A few small bugfixes (there's still a mount sorting issue I haven't tracked down yet, but I'll keep an eye on it)
5.0.1: Big Mists of Pandaria update. Still a work in progress, there's some missing features from 4.3.2, but there's some new stuff too:
New features:

• Integration with the new Mount and Pet interface
• Enhancements to the Mount interface to support Favorite and Forbid
• Mounts are now searchable and filterable like Pets
• Mount filters include showing only favorites, hiding forbidden pets, hiding "unobtainable" mounts (limited-time mounts, essentially), hiding mounts that your current character cannot use, as well as the normal "show known" and "show missing" options from the pet list.
• Mount UI displays current riding skills.

Missing features:[list][*]Pet UI search box does not currently support the "tag:" format for searching on tags from 4.3.2[*]Neither pet nor mount filter boxes currently have the Tag filtering dropdown support from 4.3.2[*]Tags, favorite, and forbid are not displayed yet on tooltips[*]Mount display missing information (no tags, no source detail, no mount flag display)[*]New mounts are not currently in the database (they'll *work*, they just won't show up as "unknown" and won't have tag data until I get it updated)[*]New pets do not yet have tag data beyond ones I can get from the game (battlepet, wild, tradable, unique, sources, types, that kind of thing). This will be updated as I get time.

Pre-Mists of Pandaria changelog (until I decide it's dumb to keep here and delete it):

4.3.2: Added a new command to control how aquatic mounts are selected for smart summoning (Always if swimming, Never if swimming, Only in Vasj'ir)
4.3.1: Added mounts and pets for patch 4.3.
4.2.10: Changed version numbering slightly, and updated Sinister Squashling's source information for 2011.
4.2.0.9: Added 2011 Hallow's End pets, Creepy Crate and Feline Familiar.
4.2.0.8: Fixed Mekgineer's Chopper and Mechano-Hog faction restrictions, and added a tag selection dropdown to the right of the search box that contains all active tags for companions of the current type.
4.2.0.7: Added new filtering options: Hide collector's edition pets, hide known pets. Also split up horde/alliance-sourced pets into two separate entries where appropriate (vendor pets are still shown for both, with hostility indicated in the source information).
4.2.0.6: Added support for the Brewfest Keg Pony (suspends pet autosummon for 3 minutes) and an approximation for The Innkeeper's Daughter (suspends for 2 minutes). This will be expanded as more timed non-spellbook companions become available or people report to me ones I've missed.
4.2.0.5: Added "insect" and "crustacean" tags, fixed mount type filtering, and added in a pair of help pages showing all currently-in-use tags for pets and mounts.
4.2.0.4: Fix for companions not in Zookeeper_Data, and added the missing ZG mounts.
4.2.0.3: Updated toc in Zookeeper_Data too
4.2.0.2: Updated the toc, and added a check to try to fix a reported data issue building companion lists.
4.2.0.1: Updated for new companions in the 4.2 patch.
4.1.0.1:

• Updated for new companions in the 4.1 patch
• Additional information added to tooltips -- companion cost and notes (in a few cases, such as Lil' Ragnaros's cooking fire ability, or the Argent Tournament squire/gruntling)
• Added the Wintersaber Cub quest pet to the item exclusions
• Fixed auto-resummon at the barber shop
• No longer uses hard-coded mount speed/type information, instead uses the values returned by Blizzard (this seems to behave, but let me know if it misses something).
• Better checks for mount usability, especially when using the smart keyword.
• New option to revert to pre-4.1 pet functionality (4.1 lets minipets stay with you across zone load borders, this option lets you go back to the old functionality where they vanish at zone load instead if you prefer it).

4.0.3.7:

• Fixed a rare timing error with profession checks
• Added a few tweaks for druid shapeshift /shaman Ghost Wolf usage, and documentation in the description. It's still rough, so feedback is appreciated.

4.0.3.6:

• Unbroke /mount after I broke it with 4.0.3.5's /minipet change

4.0.3.5:

• /minipet should again attempt to summon a new minipet even if used while you have one currently out (not sure why I broke that in the first place, to be honest)

4.0.3.4:

• Data fix for the Magic Carpet (wrong creature ID). Shouldn't require an import+overwrite to fix, but if it doesn't give that a try (in the options menu)
• Fix for Tol Barad summoning logic