HTC Dream / T-Mobile G1 USB to 3.5mm headset adaptor pinouts

[PJK2011]

I have an HTC Dream / T-Mobile G1 with the USB headset jack.

I bought a nice adapter on that auction site that is really nice. It has USB ports in micro and mini sizes, and 2.5mm and 3.5mm headset ports.

Most adapters I've seen are audio-only, but this one says it supports microphone too. Before I buy a headset, I'd like to know if it's safe to assume the universal headset pinout will work. I'm thinking of a Blackberry or iPhone compatible headset. A local merchant wanted to sell me a Samsung, but I am wary of that because of the pin-reversal on some Samsung models.