I got the Mytouch 4g this morning. I have been using it all day. Just about an hour ago and ota update was sent over. If I was to guess it is going to ask me to start paying for the tethering that I currently get for free. I have since delayed it.
A friend of mine uses Tango for video chat on his iPhone 4 and he told me the speaker issue is because of the network speeds. If hes in a chat on a 3G network the volume is low but if its wifi to wifi it will be louder...the fix is just use a headset and you'll be fine. The technology is still in its infancy so just find whatever workarounds you can. I personally don't mind using a headset, it will decrease the battery drain if its wired.
Are the OTA updates still being pushed out. I bought my phone on launch day and have been using it since. I still have not received the update. My girlfriend got the phone about an hour before me with in an hour she had her update already.