It's great that you got one that isn't locked, but worth mentioning for others thats Samsung is indeed locking the bootloader on some (many?) of the wifi-only 10.1 devices.
(As far as I know, all of the Galaxy Tab 8.9 and Galaxy Tab 7 Plus devices are sold unlocked, for now.)
Well, heck, maybe I'm wrong. :-) I haven't actually done it yet, but I can pull up a "Warning: Installing a different OS can void your warranty, are you sure?" message.
I don't have a 10.1, but I did spend a few hours reading through many of those threads last week before I decided against purchasing one for my wife. (We ended up going with the 7+ model instead.)
For what it's worth, my understanding is that there are workarounds to flash an unsigned kernel, it's just a real pain. Also, I think you would get the message you are seeing even if it were unlocked... my Galaxy S2 gives me the same warning before letting me into download mode.
Also, I think you would get the message you are seeing even if it were unlocked
Right. I was thinking that if it were locked it wouldn't have such a thoughtful warning and the option to proceed. But this reasoning could be wrong obviously.