I appreciate the need for a Contributor License Agreement (CLA) in open source software projects and even understand that some tools are starting to make this process easier (like the low-friction CLAHub for GitHub and Project Harmony). However, rather than requiring a third-party form submission for an electronic signature, would adding an extra sentence and the CLA itself to CONTRIBUTING.md, which GitHub links to when a contributor files a pull request (displayed as "Please review the guideline for contributing to this repository"), allow for a valid electronic signature (e.g. "Submitting a pull request to this repository on GitHub with your name and email constitutes your agreement to and electronic signature of the following Contributor License Agreement...")? Perhaps that argument hinges on the definition of "electronic signature" (ESIGN, UETA, etc.):
"Electronic signature" means an electronic sound, symbol, or process attached to or logically associated with a record and executed or adopted by a person with the intent to sign the record.
And I would like to propose that the GitHub pull request "process" is "logically associated" with the CONTRIBUTING.md/CLA "record" and that the contributor has the "intent to sign" by adopting the process...
(Since the Open Source Licensing Q&A site is still a just a proposal, I will accept IANAL answers here.)