I've seen several reviews of Lion's server package that assert that of course you could do all of this on a Linux server just as well, if perhaps somewhat less easily. But they never seem to actually out and out say what the alternatives are.
What would you need to able replicate the abilities of OS X's server version in Linux? I'm putting down a list of the features listed on Apple's website below, but would be interested in stuff beyond that, pulled from here: http://www.apple.com/macosx/server/specs.html
- Server.app - a one-stop application for administering said server
- Calendar, Wiki, Address Book and some sort of IM/Chat server
- Mail serving
- Web hosting
- Some sort of directory services and authentication
- Client management
- Network and VPN management
- Some sort of distributed computing system like Xgrid
- Various monitoring and performance tools
I'm something of a server newbie, so I'm sure I'm missing something.