For those who have never seen a Star Trek movie or watched an episode on TV, a "Holodeck" is a kind of Second Life for the crew of the spaceship Enterprise. But it is more than that: the players become actors in a virtual story, experiencing the events of a famous story or play. To enter the Holodeck is to take a scripted part in some well-known drama.
Holodecking is not just role-playing, it's role-playing with a script. It seems well suited to SL, as we can easily switch avatars, and even scenery. A group of players could get together and put on Romeo & Juliet, each player taking on several different successive parts, just as Shakespeare's players did. Unlike the Stratford players, the SL players don't have to memorize lines--just read them at home from the script. An audience isn't necessary, or maybe even not desirable: just play your roles with your Holodeck friends, like they do in Star Trek.
MMORPG's have tried to encourage "role playing", but even if there is a background story, everyone is assigned to menial roles, fighting and crafting endlessly. (No one in Star Wars Galaxies is allowed to play Darth Vader or Princess Leia.) In single-person games, the player is bullied into saying and doing what the plot demands: holodecking is the opposite of this--everyone willingly and wittily recites the lines of Mercutio or Juliet's nurse.
There are some obvious SL problems--we can sit, but not lie down; we can shoot people, but we cannot embrace nor can Romeo kiss Juliet. Should offstage players become transparent? Is it possible to wear the name of our holodeck characters, not our SL names? How do we stage night scenes when the SL sun is obviously shining?
There should be other things to do in SL besides building and scripting. I love treasure hunts and stuff, but making costumes for a play seems just a degree better than making costumes for sale. How about putting on Othello in the new Venice?