These are actually made by Ultimate Ears who are famous among the audiophile crowd.
I've got an Olympus E-510 and this four-thirds prime lens lets me shoot in much lower light than I previously was able to get. It's a great addition to the original kit lenses.
I got this to get a high quality voice over for all the screencasts I do. It is really quite nice. I kind of wanted to get a "real" microphone, but would then need to get a mixer to power it and some other equipment. This was "plug and play" simple.
I wish I had a case for it - otherwise, it's perfect. Probably 10 minutes at a fabric store getting some neoprene and then sewing it would provide all the more "case" that I need.