Starting this week, Google has announced a change to Google Adwords policy in that you cannot use different domains as your display URLs within the same ad group.
This does not seem to say anything about the destination URL.
The display URL is simply the short, ‘attractive’ URL you have on display in your actual ad. So, for example, if you were a media company selling PPC, you might want your display URL to be www.moomumedia.com/ppc. Because this URL is in the ad, it has a character limit, which is 35 characters.
Your destination URL, on the other hand, has a character limit of 1024, which to me seems massively generous, and what it means is that you can send it to any deeply embedded page in your site, no matter what it is.
By having different display URLs for different ads, you could signal to your customer the uniqueness of the page you will be sending them to. With the unique destination page, there is no signal, you just send them to the appropriate destination page.
I am not too concerned for my own ads with this display URL change, because I have no experience in wanting to send ads in the same ad group to different domains. If ads are within the same ad group, I am generally wanting all that traffic to be going to related products – which have not in my experience been on different domains.
I think in most cases this will not be too disruptive as it will probably help you organise your ads better if