After my visit to see the Apple Genius the other day.
My daughters iPhone mic stopped working, could hardly hear her speak and next day nothing. Co-incided with the 4.1 update as well, so either it was hardware related, 4.1 or just a coincidence.
She came home to visit this week so I made an appointment at the Newcastle Apple Store.
I said I'd take it for her while she shopped with her mum.
My turn came and explained the problem, possible update or hardware problem. The Genius solved it pronto, scraping what she thought was candle wax from the mic socket and hence unblocking the mic. Rang my daughter and it worked fine
Turned out it was cake icing from wedding cake she had in her pocket.
Kids eh