Starcraft: Dark Templar, book one: Firstborn
The Starcraft II Team has not yet revealed a special unit hinted at the end of book one of the Starcraft: The Dark Templar trilogy novel—written by Christie Golden. This novel trilogy has great importance and weight, for it is an intro to the plot of Starcraft II.
It will be hard to talk about this unit without spoiling the plot of the novel.
Basically this new unit should have enhanced psionic/telepathic powers. Probably the very reason lockdown was removed from Ghosts is to balance overall game mechanics with the introduction of this new and unrevealed Terran unit that seems to have Protoss-like powers. Will it be the Spectre? Or a different unit? That is yet to be known.
I recommend fans to read Starcraft: The Dark Templar trilogy.
Book one became available on May 25,2007—few days after the official announcement of Starcraft II at South Korea. Book two comes out on November 2007.
You can read a very slim summary of the events of book one here, which explains some of what leads to believe there is a new Terran unit not yet revealed. The end of the novel is not revealed in that summary. However, Post# 5—if you scroll down a bit, will reveal the end of book one, and that will let you know why there will be a new Terran Unit with Protoss-like powers. If you don’t mind spoilers.
You can buy STARCRAFT: THE DARK TEMPLAR trilogy here.