I haven't found any threads on this topic since the 4S launch and since new headsets are coming out all the the time I'd like to see if any of you have found ones that work well. Here are the ones I've tried; Plantronics Marque M155: have to hold button down for a few seconds for Siri to come up. Picks up a lot of background noise so Siri rarely deactivates without clicking on the microphone on the screen. Motorola H17txt: Mostly the same as above although slightly better at reducing background noise. Jawbone Era: Absolutely destroys background noise but you have to hold down the tiny button towards the back of the headset. Motorola H19txt: Just came out, only have to click the button on the headset (what I'm looking for) and does OK with background noise but not nearly as well as the Jawbone.