It's really hard to understand why there is no security slot (Kensington slot) on the iPad. Doesn't Apple think that people will travel with their iPads and need to secure them in their hotel rooms when they go out to dinner?
So I hunted for a solution. I found a clear case that comes with a security cable, which sounded great until I read that if a thief tries to break the case, the iPad will be damaged. Since it's unlikely that a thief would know this, you can be certain that your iPad will be damaged in the attempt to steal it. So this security "solution" just gives the alternative of having your iPad damaged instead of stolen. What is the advantage in that? None.
I kept hunting until I found a real solution. Vaultz.net has a hard shell netbook case that locks, and the case itself has a Kensinton security slot on the outside. The interior of this case is large enough for the iPad even with the iPad in it's own case. And you'll have room for the cords, your cell phone and more. The model number is VZ00108, and you'll find it under Briefcases. It costs $30. (Vaultz.net). Check it out.