The TeX Live mailing list shows increasing traffic: the TeX Live 2015 pretest version is available, and many users already downloaded and tested it.
It contains the LaTeX2e 2015 release, which brought a notable change: the fixes, which were previously available by explicitly loading the fixltx2e package, are now enabled by default. You still can revert to the old behavior: the new latex release package enables you to switch on backwards compatibility to a chosen release date. A small but useful improvement is a new float storage allocation mechanism. By default, LaTeX could handle 18 floats at a time, a higher number would cause an error. Now, you can say \extrafloats{600} to allow 600 more. Under the hood, it improved the support for Unicode engines, and the release uses a new build system.
pdfTeX now supports EXIF metadata in JPEG files.
The shell script fmtutil has been reimplemented in Perl. Now it works with multiple formats at once, and it’s better customizable.
If you would like to download and to test it, note that it’s not yet stable so you may see errors. However, that’s what the test phase is for: you can try it out and report errors or possible improvements to the TeX Live team.
For more information, visit the TeX Live pretest page.