Being as iOS 8.1.1 was released less than a week ago, it's likely that any iPhone you pick up today will have iOS 8,1 or earlier installed. iOS 8.1 is the latest jailbreakable iOS version. iOS 8.1.1 patches the Pangu jailbreak.
It depends on where you're getting it from, when it was shipped, and how fast the stock has been flying off the shelf. A friend of mine picked up a 32GB iPhone 6 this afternoon and it came with 8.1.1. Being that 8.1 is still signing, he downgraded and Pangu-ed it (Yes, I just used it as a verb )
Yea I'm getting it tomorrow from best buy I ordered it offline and they are holding it in store. Hopefully it'll be on 8.1But if it is on 8.1.1 hopefully I'll still have time to downgrade it and jailbreak.