excellent program, thanks alot for your hard work.
just a note: you are missing python-osso in the dependencies.

[EDITED]

further notes after testing for a while:

*the image is not centered correctly if the user zooms in, this is quite apparent at higher zoom levels, part of the image file is not visible (cropped).
*scrolling speed is too fast at higher zoom levels.
*zoom level is lost if the device is rotated.

suggestions:

1)please add the fuctionality to rotate the images (maybe add 'R' for keypad control)
2)add support for other common image types other than jpg (bmp, png, gif etc)
3)since you are launching a separate window for an image, why not allow multiple image windows at the same time similar to the behaviour of the default browser ?
4)implement functionality for taking command line paramenters,
ex. python ./maepygallery.py /home/user/MyDocs/img.jpg should open a new window and show the image.
5)mimic the zoom funtionality of the default image viewer using the volume keys, this allows zooming in further when the keypad is closed.

Thanks again for for your hard work.