No charge for tethering however there is a slight art to getting it to work on TMO. You have to have DM up an connected to the BB. You can then use DUN via USB or BT to access your BB as a modem.
On EDGE I've gotten 120kbps down. on WiFi or TMO hotspot I've gotten 250kbps down. I was hoping that TMO 3G would be 1.5mbps down.
visit the mac users corner for tethering instructions. USB is stupid easy!
i'm getting 500kbps-1mbps down on a usb tether and 384kbps up. Not scorching but for normal internet browsing and emailing is perfectly adequate. Would love to see some faster 3g speeds still though... My buddy's G1 seems to be doing better than the 9700..