Say what you want about Blizzard's ability to get Diablo III out the door in a timely fashion. But you can't knock the developer for its support of older games, especially in light of Diablo II's new patch.
Version 1.13 of Blizzard's nine-year-old action-RPG is now yours for the public testing. Simply opt-in to Diablo II's public test realm on Battle.net, update and you'll be good to go. More detailed instructions are at the Battle.net forums.
So what's changed? Well, the option to respecialize a character for one thing. According to the beta patch notes, 1.13 will give players "1 free respec which can be saved" after completing the Den of Evil quest.
Of course, there are major and minor bug fixes, tweaks to each of Diablo II and Diablo II: Lord of Destruction's seven classes and at least one mystery addition. For the full list of patch notes, click click click your way to Battle.net.
1.13 PTR is LIVE – Patch Notes & FAQ [Battle.net]