IMHO and not wanting to argue, I am just trying to confirm for everyone (only someone from Samsung truly could) the interpretation of the firmware build numbers. Every Eclair (2.1) build has I570E at the start, and no other prior build (and their are many) based on 1.5 have E after I570(0). 3 in the UK and many other European mobile providers have shipped I5700's with I570EXXJC1 - bit odd to ship 'experimental' builds on shipping phones (we all expect bugs in software but not to openly supply 'experimental' software). Also software companies of all kinds generally use the 'beta' tag to show software is not UAT'd and not the 'shipping' or 'production' version.
The E in I570EXXJC1 is for Eclair