Hello, I've searched high and low for info on this problem. Google, shotwell bug reports, shotwell mailing list, and the forum here, hopefully someone can give me some insight into this.
Ubuntu 12.04 64-bit, have seen this problem both on an older Lenovo Desktop and a brand new Asus Laptop.
Have both an iPhone 3GS and an iPhone 4, initial use of Shotwell went okay, was able to import photos without much trouble, but after the first import any further imports don't happen due to getting "Unable to lock Camera: Unspecified Error (-1)"
I've tried various ways of connecting/mounting the iPhones with shotwell already open, or closed, using the automount dialogs, or telling the dialogs to do nothing and opening in shotwell, or unmounting/mounting through nautilus. Not sure where the problem is taking place or what else to try that would allow shotwell to lock the "camera" and import photos.
Any advice is appreciated.