Unfortunately I don't believe RoboHelp yet offers a help format targeted for those devices.
The latest versions of RoboHelp offer an ePub format, but that's an eBook format. Not a help system.
Helpful and Handy Links
I'm just curious here. Sometimes the term "help system" can mean several things. Would this be some kind of context sensitive help system to support an iPad/Android application, or would it be more a free-standing "knowledge base" of information?
If it's just a knowledge base, it occurs to me that even a conventional WebHelp or maybe ePub output might work. The WebHelp could be viewed in a web browser and the ePub format can be viewed from an ePub Reader of which there are many freebies out there.
I have an ePub reader for my Samsung Galaxy S 2. I use an Android app called Aldiko and I've seen one for iPad and iPhone as well. You can access the TOC and it's quite comfortable to read. I can download the ePub file to my SD card or directly to the phone and read it offline easily.
This may not be what you had in mind, but I thought I'd just throw it out there.
As for the future, I see that Adobe Captivate already has an HTML5 mobile version in Adobe Labs which you can test for free. I can't know for sure, but logic tells me Adobe RoboHelp will accommodate HTML5 at some point.
Adobe Certified RoboHelp and Captivate Instructor