Living overseas and have 1.1.4 iphone. Moving back to US end of June and will use At&T (have the At&t sim/never activated). Will relocking via at&t give me an ibrick? Will At&t activation automatically relock or do I need to get Apple involved?
Nope. The only time it ever got relocked was going to 1.1.2 to 1.1.3 due to the Locate Me feature being in the baseband.
Resetting it will keep it unlocked, but that shouldn't matter. Just do a restore in iTunes and when it tells you to activate via itunes stick it in the dock. You can then choose your plan, etc.
And if you ever visit someplace outside of the country you can still pop in another SIM. Because it'll still be unlocked.