You don't say where you are, what carrier you're on, or what version of the OS your phone is running (it could be rooted and be a custom firmware, which will not be updated over the air).
However, the HTC My Touch / T-Mobile myTouch 3G (US name) / Rogers HTC Magic (Canadian name), is currently on 1.6. everywere other than in Canada which is on 1.5.