No it will not be, but it is very easy to relock the phone if you choose to do so. Personally I will be leaving mine unlocked until I find the ultimate ROM. However, our friends over at PPCGeeks.com have the Diamond Relocker program on their website.
http://forum.ppcgeeks.com/showthread.php?t=36062 This program will help you relock your phone if you so choose to. It runs pretty much the same as the unlocking program. It will look like it is going into a flash mode but it is just locking the phone.
