There is currently a Web Feed plugin that provides a single RSS feed for the current issue -- you can find the code in /plugins/generic/webFeed/. This plugin could most likely be extended to provide the functionality you want. I'm guessing that you are a developer and are comfortable looking at the code; you may also find the following resoureces useful: http://pkp.sfu.ca/ojs/docs/technicalref ... index.html
-- OJS technical reference, which includes a section on plugins. Somewhat out of date, but should be a good starting point on coding conventions, etc. http://pkp.sfu.ca/wiki/index.php/Writing_a_Block_Plugin
-- information on how to write a block plugin. This information is extensible to other types of plugins.
And of course, you are more than welcome to ask us any questions you might have. We would also be very interested in hearing about your plans for an iPhone/Android app. There are already two apps and a plugin that you might want to take a look at: viewtopic.php?f=28&t=6828
If you have any other questions, please let us know.