Even 4.3.1 is jail broken, just whether it will be tethered or not. A tethered jailbreak on an iPod touch really isn't a huge deal, and i am sure now that 4.3.1 is out, an untethered version is right around the corner....
MY friend got a refurb 3G Touch from apple last week and it was on 3.13. I was surprised, so I looked at apples refurb page for the 3G Touch and it states it will have firmware 3.1.3. The refurb pages for 4G Touch do not specify Firmware loaded however.
We updated her 3G and iTunes loaded 4.2.1. on it. This was yesterday. 4.3.1 has been out for a few days if not a week.