Yes you can. You just have to make a device.model. This return the also the version. For exemple you can have iPad1.1 (for the first one)
function onDeviceReady() {
if (device.model == "iPad1,1") {
//DO SOMETHING
}
else if (device.model == "iPad2,3") {
//DO SOMETHING ELSE
}
}
For exemple, I use this to active or not the possibility to take picture from my device. if it's iPad1 I disable the functionnality.
Hope it helps ;)