A factory reset isn't exactly something to be taken as lightly as the CS rep that the OP spoke with may have led him to believe -- for the most part, the reason people wait for OTA updates is because they traditionally DON'T wipe your data (require a factory reset) in the process. I can't imagine there is any way a major cell carrier could get away with pushing an update that forced a reset without angering a LOT of customers
To answer some of the other questions/comments raised here, yes, a factory reset wipes personal data on the phone. A large portion of that data will quickly be restored, thanks to the fact that Google, Verizon and/or HTC do sync a lot of those settings and data. Your apps, for example, should all automatically be re-downloaded and installed from the market...but none of the previous data will be there, so you'll have to sign in and re-configure settings and all that jazz (your progress in Angry Birds? Gone). Also, yes, your home-screen icons, call log, and sms messages will be reset and can't be recovered unless you did a manual backup. Contacts and calendar aren't that big of a deal because they sync with the Google servers online, but if you have other calendars or contacts saved to the phone storage, you'll want to make sure you back those up first...because they'll be wiped out.
In short, I highly doubt what the OP was told was true (that the OTA update was meant to have a factory reset included)...but one thing is for sure: this was a bad update, and I'm willing to bet a lot of people at HTC are sweating right now trying to fix it. This is premuim, high-visibility device that Verzion is pushing hard, so they'll find a resolution for this ASAP.
I'm just glad I don't have the update.