The Battle.net Forums offer a progress report on the version 1.13 patch currently under construction for Diablo II (thanks Ant and Planet Diablo). Word is the patch, first announced in April, is going to hit the test realm "soon," but they still have no outlook on when it will go live for the full game:

Work commences on patch 1.13. We won't be providing any information on when the patch will be available, except that we expect the PTR to be available "soon". We will provide some amount of warning very, very shortly before the PTRs become available. Please keep in mind that any number of factors could delay the start of the PTR and ultimate release of the patch. Thanks for being patient, we're getting close now.