I recently posted this: Customer Brief: Autonomic Software, Inc to the bleep consulting site. While I cannot disclose too much about how "we have done what we have done" I can say that I used the Mono runtime to allow for them to deploy their software onto both Mac OS X and Linux.
When deploying at a client site recently, I used Package Maker to build a meta-package to install Mono.framework and their software simultaneously. Using the power of launchd(8) the installer installed a LaunchDaemon job file (.plist) and started the job with launchctl all from within the installer. On the Linux side of things rsync(1) to sync things into the appropriate places and then fire off the init.d script.
Overall it's been quite an interesting experience bringing Mono into the corporate world; it's almost like you're telling somebody something that's too good to be true: "wait, I can run this under .NET on Windows, and Mono on everything else? Really?" Unfortunately because of my NDA, I can't disclose too much about the actual project, but it's certainly proved that not only is Mono "enterprise ready," it is probably a better choice to write and deploy software than most other cross-platform frameworks out there.