Redirecting home to a page based on query string

Hi,

Summary: I am trying to redirect my home to a static page based on a particular query string. How can I do that?

Details: I have modified my wordpress blog to work as a multi-author blog. Each post might involve multiple authors, so no built-in feature would work for me. I would like the content of the home page changes based on the value of query string as follows:

http://myblog.com -> Show recent posts
http://myblog.com?by=author -> Show a static page in which I list all the posts by the author

Please let me know whether there is a filter or a plugin to achieve this?

Thanks,
Afshin