I don't have a lot of experience in server administration, but Server Admin Remote seems like a powerful tool. While most of the app is modeled after Apple's own tool (with Apple's blessing -- they've spoken with Apple's OS X server engineers, who told the guys that they were extremely impressed with the app), there are some parts of the program that are actually unique to the mobile version. You can not only browse various servers around the world, but you can view data for each server, check the logfiles remotely, and even do things like see the process lists or actually restart the server directly from the iPad app.
The guys say that while the app is more of a monitoring tool rather than a full administration tool (an IT specialist might see that there's a problem on the server with the iPad app, and then go to his actual terminal to fix the issue), there have been moments where it's saved the day. One of their users told the story of seeing the early signs of an attack on his server with the app, and then remotely shutting it down, completely within the app, before anything went wrong.
The app was launched right when the iPad store went live, and the Harlekins guys say that they had no real issues creating the app without actual iPad hardware. One problem that came up was making sure that orientation changes worked -- they couldn't find a way to test that in the simulator, and so they had to patch it in later on. In the future, they plan to add a PIN to the app itself, in order to increase security should your iPad get lost or stolen.
They also showed me a new app they're working on called Workgroup Manager Remote, and as you may have guessed, this is a similar tool that's comparable to Apple's own Workgroup Manager tool. This one, they said, was even better than the actual desktop interface -- the original tool was designed by technical developers, not artistic ones, and Harlekins thinks they can do the job better. The app did look good -- it makes use of the Contacts app style, showing all of the members in various workgroups, and allowing you to browse or edit their information as necessary. One limit of the app is that you can't activate or deactivate users yet -- but they're working on it.
There is one cool feature in Workgroup Manager Remote that stood out to me. While setting up servers in that app, you can go in and enter the information manually, grab it from Bonjour discovery, or you can actually take server information directly from your iPad's installation of Server Admin Remote, if you happen to have that app installed and configured. That surprised me -- in my experience, apps can't talk to each other that directly. But Harlekins says it's official Apple API -- the two apps just borrow the information off of each others' keychains. It's not well documented API, they say, but it works and it's approved by Apple.
Server Admin Remote is US$11.99 in the store now, and while, again, I'm not an IT expert, it does seem like a powerful tool for administering OS X servers. Workgroup Manager Remote is coming in the next few months, and it will intro at a price of $8.99. Both apps are obviously very technical, and meant for server admins who are already familiar with Apple's official tools, but in my short demo I was very impressed with how powerful and well-designed they seem.