I have had many conversations the last 6 months or so about the idea of using Ipads or tablets for check-in. We love the idea as well and spent some time researching the feasibility of it. Here are some notes that are up to date as of a week or so ago that those of you thinking the same thing might be interested in. In other words, here's the research you are looking for on this question. Clearly this blog is dated, so stay tuned as we see how technology continues to progress.
This is a note from Mark, our Software Architect and co-founder:
Here are the current limitations of using the ipad natively (i.e. using the Safari browser right on the iPad).
1. No label printing as there isn't direct support from the Safari browser for the required type of printing we need for labels.
2. A couple of the dialogs pretty much fill up the entire screen and/or are a little crowded but they still function pretty well with minimal scrolling.
3. This isn't really a limitation but more a note that to scroll on an iPad you use 2 fingers (side by side) and push or pull the scrolling. This mostly applies to the startup page where you scroll through to select groups you are checking in for.
So if you can live with the current limitations it works pretty well.
The other possibility which is much more involved on the setup side of things would be to use a Remote Desktop (RDP) app on the iPad to connect and control a PC with the label printer connected to it. So really in that scenario everything is running on the PC but you are controlling it from the iPad. Below are some notes I put together with some previous testing I did with that scenario and my impression of how it worked.
I did some testing using the Mocha RDP Lite app on the iPad and if I set the session to 1024x768, launched IE and set it to full screen mode after getting into the checkin system it was pretty decent really (I would say 3.5 out of 5 stars). Really it was very similar to Safari except when you clicked into a text box field in the RDP session it didn't automatically bring up the keyboard like it does in Safari so there is a floating button at the bottom for bringing up the keyboard. Also there was no Next/Previous button the keyboard (really the Tab key) but in reading about the full/paid version of Mocha RDP I think it has more keyboard options there. There are also quite a number of other RDP or VNC clients that might have different/better keyboard support so it may be that you could get a pretty close to native experience with the right RDP client.
On the RDP side you would need to have Windows XP/Vista/7 Professional to support accessing the machine via RDP (the Home versions don't support RDP) but the VNC solutions would just require installing a (typically) free VNC server app on the machine to be controlled.
Longer term I would expect Windows 8 tablets to be the nicest solution as they should directly support printer sharing of label printers hooked to a central PC.