It would be interesting if someone made an EC2 image that implemented the Lambda APIs, and handled as many requests as it could, then optionally delegated the overflow to real Lambda. Like "reserved" Lambdas.
This is a _fascinating_ idea. You could make an image that queried the Lambda API, downloaded all Lambda functions (and their configuration) and served up exactly those functions. Make it completely turnkey.
Hm...
You might want to check out IronFunctions that was released last week: https://github.com/iron-io/functions . You can run Lambda functions anywhere, can even export/import them directly from Lambda. It doesn't have the burst to Lambda part you speak of though... yet.