Droid-Life is reporting that work on the Jelly Bean update is well under way for the S3 (which most people expected), and that it's likely to see a release by Q4, possibly even Q3. That's probably for the carrier-free international version though. While I'm sure Samsung is working on the carrier-branded builds, including Verizon, that process can be lengthier. I'd be incredibly shocked if we see it in Q3, so I'd be on sometime in Q4 before the end of the year.