Logged into my account to find that there is now an 'Optimized' pixel option to choose. What the hell is this and how does it differ from the original 'conversion tracking pixel" above it?
I don't have - screenshot?
No, I'm not sure that this is exactly the case anymore. If you select "website clicks" as a campaign objective, then you will see one pixel in power editor: the conversion pixel. I believe this is used solely for reporting purposes.
However, if you select, "website conversions" as an objective, you will see two pixels: an conversion pixel and an optimization pixel. When you select your bid type you will now have the option to optimize for a pixel, which I believe you don't get when using the other campaign objectives.
I know that this was not previously the case. I think the campaign objective was simply used for reporting purposes. Not it does seem to make some serious material differences, especially with regard to having the addition of the optimization pixel.
Please let me know if I am mistaken though 
Oh yes I see it now, only turns up on new campaigns.
You're right - the conversion-tracking will just be for reporting whereas the optimized conversion pixel will be for oCPM optimisation of audiences.
They have probably split these to avoid confusion and create more granular reporting.
A picture tells a thousand words...
