Since I'm rooted and running a ZVD-based custom ROM, I have no interest in ZVJ. I'm not sure why others are so interested in getting ZVJ. Gingerbread provided almost no benefit over Froyo. I'd bet that any of the ZVD or ZVH custom Gingerbread ROMs are way better than the ZVJ stock. And I don't think it'll be too long before the ICS-based custom ROMS will be working well on ZVD & ZVH. (Based on my test-drive of Kraven's current ICS alphpa port, ICS is a HUGE step beyond Gingerbread.) If I had a stock ROM I'd refuse the ZVJ update until somebody could guarantee me that ZVJ could be rooted and downgraded to ZVD or ZVH (or that an ICS ROM had been ported to ZVJ).
For anybody who wants to refuse the new update and the nagging reminders, following is the method that many of us used several months ago to refuse the ZVD & ZVH updates. I guess this method still works.
1. When you get the update notice, go into the "More Info" page of the update.
2. Pull the battery (I think immediately, while the phone is trying to get to the page).
Pulling the battery after clicking "More Info" on the update notice prevented any future nagging notices to update.
One possible downside of doing this is that if you ever do want to do an over-the-air (OTA) update, I don't know how to invoke an update. I'm sure there's a way, but I don't know how. I actually tried to do an OTA update (from ZVC to ZVD so that I could root and flash from there) using the built-in menu options, but it said there was no new firmware available. I ended up having to manually install the ZVD ROM.