Is there a setting in the Motorola or Cisco HD DVR to upconvert 480i, 480p, 720p, and 1080i source material to 1080P, and then output the 1080P to the AV Receiver or the HDTV via the HDMI connector?
No there is not. The HD output of the STB is either 1080i or 720p, or passes through the native resolution, depending on what you set it to be. In this case of a 720p or 1080i setting, the STB upconverts SD signals to either 720p or 1080i or converts 1080i to 720p, or to 1080i or converts 720p to 1080i depending on the setting.
Your AV receive can receive the 1080i (or any other) signal and may be capable of upconverting it to 1080p (mine is). But if you have a 1080p TV, the set itself will upconvert and display any signal in the TV display's native format, and probably has superior upconverting algorithms over those in a receiver or the STB.
One last comment: The quality of 1080p is not always any better than 1080i. It all depends on how the source was digitized in the first place. And in some cases a 1080p Bluray disk will look no better than a 1080i broadcast of the same content in this case.
there are only two providers that do 1080p on demand and they are satellite providers.
no cable operater that I have heard of does 1080p.
they may in the future, but they don't right now.