it's called Implanon. it's been around for probably a decade, maybe more, but not a lot of doctors are doing it because it requires special certifications and licenses and stuff. my doctor got certified to insert them within the last 2 years, and she's been sticking people left and right since then. she loves this thing.
i took Yaz for 2 years, and it made my moods reeeeeeeeally unstable and caused me to gain an obscene amount of weight that i'm not about to disclose here. once i realized that it was the Yaz that was fucking me up, i switched to the Depo shot, which was WONDERFUL. and i've been able to lose weight pretty easily while on Depo, so that's not an issue.
this Implanon thing is similar to the Depo shot in that it releases hormones over a certain amount of time, but it's a different, less intense version of the same hormone. i have a feeling that i'm going to be VERY happy with it, it's worth checking out.