Few things...

1. Waitlist for mileage upgrades does lots of bad things, as has been reported previously. However, please know that the effects remain even after the waitlist is canceled. For example, if you attempt to change flights after the waitlist has expired, co.com still searches only for award tickets.
2. Confirmed standby: standby segment as well as future unflown segments move to "past." The entire itinerary becomes unviewable by any means (including OLCI) at the moment the "current" segment is within one hour. Specifics: sjc-ewr changed to sjc-iah-ewr (noon departure). At 10:58 or so, I did olci. At 11:01 I tried to review the seat assignment for the iah-ewr segment (7:05 departure) using OLCI but was unable - even using the e-ticket number. Message was that there were no valid flights. The entire itinerary moved to, "past." I was able to view the record using conf # and name, but couldn't save it to my account.
3. OLCI at pda.continental.com: as noted in an earlier post, the seat assignment page when not changing seats might change anyway. Let me add that under certain circumstances (none of which are clear to me), you just get the last seat (highest number, highest row) no matter what you select. Going back and re-selecting the correct seat fixes the problem (as long as no one snagged it in the meantime).
4. CLEHillbilly: it's been documented that the online upgrade is domestic only. I would expect a better error message.