I see no one wants to touch this with a 10-foot pole. OK, I'll take the bait.
I believe that yes, it voids your warranty. I highly doubt anyone at Verizon will do it.
Now SOME people might be inclined to customize their BlackBerrys, then if anything warranty-related comes up where they need to send them in, put the original parts back on. Just sayin, it happens. But I've never done it, so I don't know if there's any way to tell. I'm sure a Verizon employee will chime in here though.