This is exactly what I want.

(1)I already have a phone and don't want to change the data plan(will cost me $30 more per month)
(2) I want to try Android 2.2 but do not want to pay a lot.
(3) something can tether with my 3G phone and get online, not just wifi.
(4) something not too big and not too small, something portable, something I don't need to carry around if I don't want to(which is not possibe if you have an android phone when in some situation all you need is just a small phone.)

This one sounds perfect for me. I really want to see the reviews of it after it has been released.