One of the things coming to World of Warcraft with the upcoming 3.1 patch is the option for players to have what's called a dual specialization. As we've heard from Zarhym, they will be available at level 40 for a cost of 1,000 gold, and essentially will be a button that will swap you from one spec to another in a matter of moments. This will also cause your glyphs and action bars to swap around as you change specs, so you don't have to screw with swapping glyphs around. (You'll still need to swap gear around, but most people who've paid to swap specs are pretty used to that - and besides, there are mods to do that.) This will be of great use to those who play hybrid/healer classes, or have different raid and PvP builds. It won't work in the Battlegrounds or Arenas, though.
All that said, will you be making use of dual specs in World of Warcraft, or are you pretty set with your current spec? If you're not going to use it regularly, will you instead use it for trying out other builds for fun? If you will be using it, have you got your two favorite specs planned out yet? What will you be switching between?