Very cool. A great way to covert legacy mailing lists to RSS. Need to try this.
From MailbyRSS Overview:
Using MailbyRSS is simple. Organizations need only to sign up to the service to receive a special e-mail address and password from iUpload and can immediately begin to author content for their RSS channel by sending it as an email. When MailbyRSS receives an authorized e-mail message, it automatically creates or updates an RSS channel and generates any supporting web pages required.