tbluma,
I agree with the audio alert...would be awesome. Hopefully they will implement that soon. Even if they did, it still isn't the best choice to rely solely on this app for security (icamsource could crash, or more likely, you could lose Internet connection, etc). Do you have window/door/glass break sensors hooked up to an alarm system? Moderm alarm systems allow you to receive text, e-mail, or phone calls in the event that an alarm sensor is tripped (which basically allows you to self monitor the alarm). I would think the traditional alarm system would make a better 1st line of defense. At the point you get an alarm event notification, you could open iCam and listen in.
Anyway, you know that you can get a wireless IP camera (or wired one) for $50-$100...and that would allow you to cover more entry points with one computer. Because it's not practical to cover every single entry point (doors and windows), I will have my cameras located inside my house covering high-traffic areas that a burglar would have to pass through or would be likely to pass through...hallway, living room, garage, etc. With dropbox running in the background, those motion images are then backed up offsite.
Since iCam 2 supports more than 4 cameras, it will be easy to add more cameras later. It's not super-cheap...but it's much cheaper than a pre-packaged security program...and with better quality cameras and more flexibility.