Wow, so I'm not the only one...
I used my Touch on a near daily-basis with the speakerphone, while charging, and not once did I notice it DRAINING.
So am just making a regular phone call, with no wifi enabled, no data connection, and bluetooth is not connected either (but is "on") -- wow, I really hope I get a new one without these issues (and with a heat-plate)
AFAIK, none of the Sprint TPs have the heat plate.