I mentioned this in another thread, but unless Broadcom has updated their BCM7411 and 7412 chipsets, they do not support 1080p. Now, I do recall reading about a BR or HD-DVD player that uses that same chipset but originally only supported 1080i, then later could support 1080p with a firmware update. Maybe Broadcom's information online is out-of-date ?
Also, and I said this earlier...
You're missing several important points.
1) Almost all HD movies and most HD scripted TV shows are mastered at 1080p24 (used to always be shot on film, now 24fps HD video is used too). The 24fps frames are pulled down to 60i using 3-2 pulldown.
2) On the receiving end, once the 60i fields are decoded, a video processor can reassemble the pulled-down fields back into 24Hz progressive frames using inverse 3-2 pulldown. This is what a good TV or video processor does.
3) The 7412 by itself can't drive your HDMI output. There has to be a chip downstream of it to implement the scaling to 480p/720p/1080i that you can select in your receiver's menu. According to other posts on this forum, that chip is a Broadcom BCM7038.
So it is totally unnecessary for the MPEG-4 decoder (the 7411/7412) to support 1080p. It just had to decode the 1080i sent by Dish. Downstream of the 7412 is a Broadcom BCM7038, which implements reverse 3-2 pulldown among its many other functions. I can't find any documentation that says it supports 1080p output, but if it can support reverse 3-2 pulldown on an incoming 1080i signal, then it most likely supports 1080p out its HDMI interface.
Many of us today are watching NATIVE 1080p from Dish broadcasts. Just because they send a channel in 1080i doesn't mean that that's what's contained in the signal. The signal actually contains duplicated fields from a 1080p24 source, and these progressive frames can be fully recovered at the receiving end to give you NATIVE 1080p today.