I just got off the phone with Ron, a third-level Sony support technician, reached through 1-800-838-7669. He was a very courteous and knowledgeable tech. He reported that my conversation with Ed Saturday morning was properly relayed to "Engineering" and they have duplicated the problem in their test lab.
The vertical line transversing the screen at one-second intervals while in 1080i is now an official Sony engineering issue with the XBR800 line of TVs!!
Ron mentioned that once it is a recognized, known, hardware problem (as this appears to be) it usually takes several weeks for a fixed board to be engineered, tested, and fabricated. He suggested I call back "every couple of weeks" to receive updates but to not realistically expect anything before the first of the year. At that time, Sony would schedule a "local authorized service facility" to visit my home and replace the offending circuit board in the TV.
Ron mentioned that there has been an "onslaught" of calls the past few days on just this matter. He said the number of complaints, and the very precise frequency info given (thanks to Andy64 and my EE professor neighbor), allowed Engineering to focus in on the problem very quickly.
I am so relieved!!!
I've got no problem using 720p for a few weeks and waiting that long for this to be resolved!
For those of you still waiting, I highly recommend you call and ask for either Ed (second-level) or Ron (third-level) support. These guys are great to deal with (Ron maybe a little more so than Ed) and both seem to properly understand the problem. If anybody wants more specifics, feel free to e-mail me directly.
This is good news, guys and girls...