Anyone know when they are going to be out, or is it just going to depend on the store most likely?
I think it totally depends on the store and your store manager...
The May 5th date was the "approximate availability date" that Hasbro quoted on the Clone's sign at C3.

The May 8th Date is the date that was quoted in the Target handbook:

Basically, Target is supposed to re-set their toy aisles for this weekend. When the toy aisles are re-set, there will be pegs for the Clone Troopers in place of the pegs for the Lava Vaders (like Pete was saying).
Some stores are treating the "May 8th" date the way they treated the April 2nd date - they have an "official" Target handbook that says May 8th, so they are waiting until overnight May 7th to re-set the aisles.
Other stores though are treating the aisle re-set the same as they would any other re-set - it has to be done by May 8th, but can be done at any poin between now and then (within 1 week). That is why some stores have already re-set and pepople are finding them on the shelves.
Like Pete said, your best course of action is to take the DPCI # (087-06-1489) and call Target and ask for Customer Service. They can tell you if they have it and can hold it for you if they have them in the back and not on the floor yet.
Jeff