Hi
Been using AWS since 2009, and proud that I am an early adopter for SQS. Recently one year back, when they came out with lambda, I had implemeted the same on a production system. The story is in AWS Case Study.
The requirement could be written as a lambda function which can subscribe the atom clock ticks or be triggered from a delayed SNS. Well running the thing at frequent interval is not a scope of the project whereas picking the feed and comparing with a previous one is a bit trival. Might need to use AWS S3 or Elastic Cache for temporary storage if at all you are going to run this from lambda.
Hope to hear from you soon. By the way, the script can be completed within a very short time though I have never attempted any similar functionality.