For those of you looking to implement a Catchall agent in Microsoft Exchange 2007 I finally have an answer for you! CatchAllAgent Exchange2007 Transport Protocol Agent does everything I needed it to do. It can handle multiple domains and supports standard .Net tracing for troubleshooting. Granted I didn't write it but it is simple to set up and configure.
The download is not as straight forward as I would have liked (multiple files vs. a Zip file) but the instructions are clear and consise for installation. The bare minimum you need to download is the CatchAllAgent.dll, config.xml, and Readme.txt. The author has included the source code for the CatchAllAgent incase you want to see how it works or if you have enhancements to make. The one issue I had with installation was due to me not reading ALL of the instructions and missing a step ([PS] C:\catchallagent>enable-transportagent "CatchAll Agent").
There are many reasons to NOT have a catchall agent setup. For one you open yourself up to a Denial of Service attack because all email will now be accepted for your domain, which may also lead to the servers storage being filled. But when the CIO and CEO both say we NEED a catchall I fulfill their request and warn them of the dangers. Hopefully I never have to say "I told you so!"