I'm kinda surprised to see this hasn't been posted here considering the large amount of people who are into jailbreaking...

iOS 7.1 & 7.1.1. Tethered Jailbreak for iPhone 4

Download @ http://geeksn0w.it

I can confirm that this works. I used it on my old iPhone.

Only works for iPhone 4 due to geohot's Lim3rain bootrom exploit on the older A4 devices. I believe that a new one for iOS 7.1.x is currently being developed by evasi0n according to @pod2g tweets.
Happy jailbreaking!