Before arguments start that the Evo came with Eclair, here's the history:
- Rev 1.32.651.1 - Shipped ROM, Elcair
- Rev 1.32.651.6 - launch-day OTA (June 4, 2010)
- Rev 1.47.651.1 - June 28, 2010
- Rev 3.26.651.6 - Aug 2, 2010 - Official Froyo (.3 leak on July 30)
- Rev 3.29.651.5 - Sep 22, 2010
- Rev 3.70.651.1 - Dec 15, 2010 (two update leaks prior to that)
- Rev 4.22.651.2 - June 3, 2010 (update leak in April)
Stellar update record compared to other brands and models.
It wasn't until that first week of August that we as a community listened to the voices in the wilderness (aka many other helpful posters here), warning to simply backup/factory-reset/restore on every update - that we had to learn for ourselves through trial and error on the major Froyo update.
Hope this helps. Also note, 651 seems reserved to this phone (noting earlier revision question on Sense).