I've heard of the OpenManage stuff, but from what I've read you need a windows app called "IT Assistant" to connect to all your OSMA agents on the servers.
Is there an open source / *nix friendly web based "Controller" application which allows you to view and do everything you can do in the OpenManage local web server application?
I don't know of a prebuilt tool, but you can wrap a UI around Dell's omsa command line tools pretty easily and they run in Linux.
In our case it was easy to do things like add a "identify" button and a data agent to our existing inventory system. Other tools like BIOS autoprovision script using PXE etc. Just setting up SNMPtraps and having something like Zenoss to capture them does most of what you really need.
If you haven't come across it already worth looking at the stuff at http://linux.dell.com/ especially http://www.delltechcenter.com/page/Linux+Hardware+Monitoring The resources there and associated mailing lists were very useful resources when we ran significant numbers of PowerEdge servers.