On the main PHP.net site they've posted the announcement of the release of the latest beta for PHP 7.2.0: PHP 7.2.0 beta 3:

The PHP development team announces the immediate availability of PHP 7.2.0 Beta 3. This release is the third and final beta for 7.2.0. All users of PHP are encouraged to test this version carefully, and report any bugs and incompatibilities in the bug tracking system.

This development only release includes mostly bugfixes (full list here) and can be downloaded from the usual QA sites: source and Windows binaries. This is the last beta release for PHP 7.2.0. The next release in the series will be PHP 7.2.0 RC1 on August 31st.