This release is mostly about improving password security and password-related functionality.
For details see: http://hg.moinmo.in/moin/1.9/raw-file/1.9.7/docs/CHANGES
See http://moinmo.in/MoinMoinDownload for the release archive.
BTW, for future moin 1.9 releases, we still need many more people helping with maintaining and updating translations on http://master.moinmo.in/ .
So, especially if you speak some non-english language, you can help!
See http://moinmo.in/MoinDev/Translation for details.
These days we spent most of our time on developing moin2, see http://moinmo.in/MoinMoin2.0 for details.
If you like to hack / test new stuff, have a look! Also feel invited to help with it, so it gets ready for production sooner.
If you are interested in helping, feel free to contact us on IRC chat, see: http://moinmo.in/MoinMoinChat