Yes, you can transfer the effects of being grabbed to someone else, and you will no longer be grabbed. Whoever you transfer the grab to will have to deal with it like a normal grab. However, the grabber can end the grab instantly as a free action, so it won't last long if you've made them grab their own ally.
Let's review how Grabbing works
Grabbing takes a free hand (or appendage) and requires your target to be in, and stay in, touch range. For most characters, that's adjacent. (There are exceptions if you're using a special grab power.) There's a difference in what it does though depending on whether you're using the Player's Handbook or the more recent Rules Compendium:
- In the PHB, Grabbing applies Immobilized. (p290)
- In the Rules Compendium, Grabbed is now its own condition, which also makes you immobilized (p231). Maintaining the condition requires you to keep using the same appendage that started the grab. The Grab power (p243) doesn't actually explicitly apply any conditions, but it's safe to say it applies this one.
Meanwhile, Transference moves a condition to someone else. That's it.
So you Transfer the Grabbed/Immobilized condition. What happens?
If you're going by the Rules Compendium, your target is now Grabbed. The grabbing appendage is now probably on your target. You are no longer Grabbed or Immobilized. Your target must deal with being grabbed as usual, just like you were a moment ago. You can walk away. The grabber will have to make a fresh attempt to grab you, costing them a standard action.
If you're going by the PHB, you've made someone else Immobilized. Things are less clear on whether you're still grabbed, or your target is. If they become grabbed, everything aligns with the Rules Compendium. If you're still grabbed, you're in some weird pseudo-state where you're grabbed but someone else is suffering the consequences of it — until the grab is sustained (if it can be), and you have Immobilied re-applied on you. This second option is ridiculous, so go with the Rules Compendium approach.
In both cases:
- If you transfer the Grabbed condition to someone out of range of the grabber (e.g. someone on the other side of you), the grab ends instantly.
- The grabber can end the grab instantly with a free action.