I've yet to hear back from anyone testing the prerelease - if you're able to, please do!
Especially of interest to be tested would be the new HostnameEndpoint, which tries to connect to both the IPv4 and IPv6 addresses from a DNS lookup, and uses whichever is first - it makes Glyph excited for its inclusion, so it ought to make you ;) .
It also supports SSL chain certificates, which should also fix up some issues using TLS with Twisted - this would also be great for people to test, and will hopefully remove a bunch of monkeypatching in everyone's code.
Unless there are problems brought to our attention, it is unlikely that the 13.2.0pre will be different from the final release - so you can also use it to run against your application's test suites, so you know you're ready for upgrading to the full release later. :)
The tarballs and NEWS file are available at http://twistedmatrix.com/Releases/pre/13.2.0pre1/ .
The ticket for the 13.2 release is at https://twistedmatrix.com/trac/ticket/6795 - please comment on it if you have any issues!