No code changes to hdparm itself, but the bundled wiper.sh script had a bug fixed, and now runs much, much more quickly than before.
wiper.sh issues SATA DSM/Trim commands for most of the free blocks on a filesystem, which can help SSD firmware better manage internal garbage collection and wear-leveling of the flash media.
Periodic (weekly/monthly) runs of wiper.sh can revitalize a fragmented SSD, bringing its performance back up to nearly-new speeds again.
This is similar to the "wiper.exe" script that exists for Windows platforms, except it is non-proprietary and works with the standard Data Set Management (DSM) "Trim" subcommand.
New SSDs in the comings months are likely to provide support for DSM/Trim, and the Linux community is now ready to take advantage of the feature.