Victory in Hillsbrad

If you can't find SS vs TM in your battleground list, try again in your garrison. It's the only place where it actually appears for me. Not sure if anyone else got the same problem.

This Achievement now awards a title, [title=418], for the Horde version, found here: Victory in Hillsbrad, and the Alliance version awards the title [title=417].

From the Official Blog

A win will gain you a shiny new title: either Tarren Mill Terror for the Alliance or Southshore Slayer for the Horde.

This Achievement is a Feat of Strength, since it will be available for a short time only.

[npc=76873], the savage battle pet who used to be the reward for the Hillsbrad Victory Achievement, was not only a Placeholder, but also a cruel, cruel joke, and not obtainable by any means, as of the release of Warlords.

The title, [title=417], is account-wide, including both factions.

Earning this Alliance-side achievement also gives your Horde characters access to the [title=418] title.

Appears to require the character be level 90 to use the title.