Smith Micro Software have released 'SendStuffNow' for Windows Phone 7 (previously available on iPhone and Android). The app is part of their "cloud-based managed file transfer service", which is fancy talk for sending big files to and fro when email is not an option.
This is mostly geared for business/enterprise environments as you have to pay for the file storage/hosting (starts at $120 a year for 2GB), but it offers a nice streamlined method by which many users or team members can actively work on and exchange large files, even on their mobile:
SendStuffNow offers an easy-to-use, secure file-sharing service that overcomes the file size limitations of email, FTP, or MMS. SendStuffNow uploads the large files to a cloud based service from which users can share them with coworkers, customers, and other collaborators. Recipients receive an invitation from you via SendStuffNow and can then download the shared files using a web browser. Recipients do not need any accounts or special software.
Actually, that does sound kind of useful. For more info, head to Smith Micro's site right here and you can download the software for your phone here. You can read more on the release and its importance to IT and enterprise here at The Street.