Good to see some conversation starting to flow about this issue. Here is what I've noticed so far.
1. I haven't seen the "medium" issue in any of our accounts. Distribution is set just fine. However, there could be an interface glitch or something where my medium is "not set" despite it saying "search network"
2. We're getting much less volume in adcenter now than in Y! and adcenter combined pre merger at similar bids. I don't have the balls to double or triple the bids for a day and see what happens, but perhaps the predicted increases in average CPC by position post integration are larger than I would have thought.
3. I haven't seen one instance of someone claiming to get more volume in adcenter now than in adcenter and Yahoo combined pre integration.
4. Partner network distribution seems relatively constant. I'd be curious if you guys have seen anything different.
This is a major bummer for everyone except Google. Maybe I did something wrong with the transition, but I'm willing to bet I didn't do anything ill advised.