I'm using a Treo Wireless Headset and people I was talking to complained that they could hear themselves echo. I worked around the problem by using a jabra eargel, but I didn't like the way that looked and it made the headset somewhat less comfortable to wear.

In any case, after I upgraded my Treo to the 1.28 firmware I took off the eargel and tried to make a few test calls and people told me that there was no echo at all... even with the volume turned up quite loud on my end. I'm not sure what Palm did with the new firmware, but this makes me very happy