The Wrath of the Lich King expansion is still a long way from coming out (no announcement yet) but the warlock class has gotten a sneak peak at what the devs might have in store for them when it does come out. Kalgan (Lead designer Tom Chilton) leaked out to the warlock forums an idea for a spell that gives warlocks a sort of "blink" ability.
We definitely feel the need for warlocks to gain some sort of active defense so we don't have to try to balance them around the assumption that they're "tanking" melee classes. For example, an idea we're running with internally is the concept of a warlock being able to cast a spell that places a circle of demonic power on the ground. The warlock would be able to teleport to this location from within a relatively short range (ie: 40 yards), and would also be able to summon demons more quickly if they're standing within the circle.
Note: this idea is intended as a sneak peek, it's not something that we're planning for 2.4, it would be more likely as an expansion ability, and may change entirely before said time. source
Having played both a mage and a warlock (my warlock is 47), my observation has always been that warlocks don't have that many escape mechanisms. As a mage, abilities like mana shield, blink, polymorph and even the frost talent ice barrier can help escape a bad situation. Ice block will do the trick too if you're in a group. As a warlock, you only have fear, death coil and sacrifice. Fear isn't always reliable and death coil is on a 2 minute cool down while sacrifice only works if you have your voidwalker out.
At the risk of getting flamed and getting told that warlocks are overpowered and that this shouldn't happen, I actually have to say that this "blink" spell is actually a great idea for the future. I'm thinking a spell like this would have a cool down of at least 1 minute although I'm guessing it would be more like 2 or 3. Of course, if this happens I'd really wish mages got something equally as cool!
update: Kalgan assures mages that they'll get something cool in the expansion too.
Mages will get new abilities in the expansion too, believe it or not. In fact, we intend to tone down how strong of a counter warlocks are to mages through the wotlk spells/talents. source