As of January 1, 2018, the new USA Baseball Bat Standard will be implemented. Most Little League-approved baseball bats that are approved for use for the 2017 season will no longer be acceptable for use in any Little League game or activity starting on January 1, 2018.
Update 2/15/18: Little League has revised their bat rules for this season for the Intermediate and Junior Baseball Divisions. Bats that meet the "BBCOR" standard will also be allowable in these divisions, in addition to bats that bear the new "USA Baseball" logo. The bats must be marked by the manufacturer (silk-screened) with either the BBCOR coefficient or the USA Baseball logo.
This allowable use of BBCOR bats does NOT apply to Majors Baseball or any of the Minor League levels.
There is no change to the standard for Senior Baseball; the BBCOR standard still applies.
Softball bat standards are unaffected and unchanged from 2017.