This would be fine, if only more third party resources were available over HTTPS at a reasonable cost.

For instance, I'd love to use Olark for occasional customer support queries, and the free plan would work great for now. Unfortunately, Olark doesn't offer SSL until their $49/month plan.

Similarly, Cloudmade's fantastic OpenStreetMap tileserver is only available over plain HTTP, period.

With this change, I would have to choose between great services like Olark or CloudMade and offering SSL everywhere on the site. I understand that select pages with mixed content could be subject to man-in-the-middle attacks, but surely that's a better risk profile than forcing me to run everything over HTTP, right?