As an developer I often have an iOS device connected to my MacBook Air when I launch iPhoto. The standard behaviour is for the last selected item in the source list to be selected on launch, except when a device is connected, in which case iPhoto attempts to show you photos ready to import from the connected device.
How can I get iPhoto to ignore the connected device and just show me last item selected, which in my case is always Photostream since I'm constantly posting screen grabs of app defects?
I'm afraid there isn't a way of doing this. Either plugging your phone in after starting iPhoto, or starting it with it plugged in immediately switches to it. I can't even think of a workaround, so the only advice I can offer you is to file a feedback entry suggesting it as unwelcome behaviour.