Continuing the discussion from Add certificate transparency monitoring service to Let's Encrypt:
The original discussion happened before we decided to look into exactly the same thing. I don’t see this as a function of Let’s Encrypt as a CA and it is likely to remain in hands of administrators. What we can do is to make this really easy.
We have just launched KeyChest - https://keychest.net (It is free)
KeyChest already uses CT logs extensively but if you’re after particular security checks, please comment here! We’ll see how to include it into headlines or other visible warnings.