I have an old iPhone 3g I've been hanging onto because I keep thinking at some point I might be able to use it as a webcam with iCam. Any plans on making iCamSource Mobile compatible with older iOS firmware (specifically 4.2.1)?
No, unfortunately, and it is largely due to Apple no longer supporting targeting any version of iOS below 4.3 when developing applications with the latest version of their developer tools. To support the older versions of iOS we would need to use an older version of the developer application (Xcode) that would not support the features and capabilities of the more recent versions of iOS.
Additionally, the iPhone 3G hardware can barely handle the basic capturing and streaming of our ipCam application. Adding the encryption and motion detection logic processing to the already-taxed hardware would simply make the app unusable.