It seems that Google has been hiding the info in plain sight, with a GitHub page dedicated to "Mobile Chrome Apps". The page is run by a software developer at Google, Michal Mocny; and, the page's documentation even shows off a toolkit that can be used to build Chrome Apps for mobile platforms. Google is suggesting that developers target Android 4.0 and higher, although technically lower versions are supported. iOS support has not yet been finished, but is in the works.
Google developer advocate Joe Marini says, "[Google hopes] to have something in beta form in January." We would assume that the Android beta is the target there, given that iOS support isn't even finalized yet.