Following procedure works for standard 2011 Mac mini and the 2011 MacBook Air (they have different build of OSX from that available on the app Store)
I'm not sure what implications it will have for the server version (e.g. will you get a version with Server extensions bundled with it, will you be able to add Server extensions from appstore for free at end of install, or will you need to buy Lion server as a paid download)
My guess is you'll get a download that includes server components, as we aren't doing anything a normal server recovery install wouldn't do.
First get an external usb drive (something bigger than 16GB) and do the following:
1 plug the external USB drive in
2 power off the mini
3 power the mini back on while holding the option key
4 select the internal recovery partition (unless you've changed the boot drive
that came with the mini there's already a recovery partition on it
you shouldn't need a USB recovery disk)
5 press enter
6 follow the 'reinstall OSX lion' prompts till you get to stage it asks you what drive you want to install to
7 choose the external USB drive
8 you'll then get the
'Mac OSX Lion Downloading additional components. your computer will restart automatically.' screen
depending on speed of your net connection this could be what you're looking at for the next few hours
9 When it completes and automatically begins to restart you need to kill power to the mini and disconnect the external USB drive
10 Let the mini boot back up as normal without the external drive connected.
11 Once your back at the desktop reattach the external USB drive
12 There should a set of OSX lion install files on that drive
13 you can now restore the install dmg file from those files to a USB stick
you now have your own bootable copy of the Lion installer without having to sit thru the online install procedure each time. If you do it at moment you should find the copy you now end up with is a 10.7.1 build as I think thats been rolled into the versions currently being served accross the net by Apple.
14 The only thing left to do now is reset the PRAM on the mini, if you fail to do this you'll get an error message when you try to reinstall Lion from the stick
(we quit installation to the external USB drive before it completed to get access to the install DMG, and as a result the PRAM is still holding the UUID of that external USB disk so the Lion installer will look for it each time its run until the PRAM is reset)
Biggest hassles with above are need for the PRAM reset and having to keep an eye on the mini while sitting at point 8 for what might be hours on end ..because we want to kill power at stage 9 (just when the machine is automatically restarting)