Linux Servers?

“I am working with a couple of large companies that are purchasing web and collaboration software stacks from Microsoft, IBM and others. These are for thousands of end users and are (supposedly) ready for multiple data center deployment and other big-corp requirements. I have suggested some open source alternatives such as Liferay and Drupal, and the technical people are interested but management types are not. They have given a few reasons, such as concerns over supportability and enterprise-readiness, but my feeling is that they are being won over by FUD from large vendors and the fact that most corps do not have significant deployments of FOSS technologies beyond Linux yet. All this seems to be in line.  So my questions are: How have you persuaded larger enterprises to adopt server-side OSS, beyond server-room Linux and a couple of demo JBoss boxes under someone’s desk? And which products are truly ready for enterprise-scale deployment?”