I've had mine for 4 weeks, and haven't seen another while I'm out. However, yesterday I see 2!! I was in the Galleria, and saw a guy walking towards me with the mic on the white earbuds, so I knew he had one.
Later in the evening, I went out to a club and there was a girl sitting at a table with a few of her friends. I saw her iPhone on the table in front of her, but didn't know what type of case she had. I approached her and asked. We got into an iPhone discussion. She said she uses hers as a "guy magnet". She said she'll turn in on, put it on the table, and guys just flock to her asking her to see it. I had to laugh at that one!!