On Sunday, we reported that Google will now be requiring one domain per ad group as part of their new display URL policy in the AdWords program. In short, what this means is that you cannot advertiser for rustybrick.com and seroundtable.com in the same AdWords ad group.
We were unable to confirm that this change is indeed going to happen until today. AdWordsAdvisor in that WebmasterWorld thread confirmed the change by saying:
I can confirm that there is a change coming up, the intent of which is to make sure users are sent to the site to which they expect to be sent.
That said, I am so far behind in general (which, by the way, also accounts for my less than sterling attendence in the forum the past week and more) that I am not yet up-to-speed on the details.
I will look into it and post again later. To set reasonable expectations, it is not likely to be earlier than late in the day tomorrow (Friday) - just looking at what I've got to get done before I can even start digging into it.
My apology for not having a concise answer, right now.
So if you are very interested in these details, I would visit WebmasterWorld again later today.
Forum discussion at WebmasterWorld.
Update: On February 20, 2009, Google posted a blog post once again confirming this change and sharing that this will be going into affect the week of February 24, 2009.