Photos appearing flat/desaturated on iPhone?
It looks to me like you have a color profile problem; in particular, the desaturated version looks like an Adobe colorspace image using the sRGB profile incorrectly.
I don't believe the iphone uses embedded profiles, but images converted or shot with sRGB profile show up correctly in both my iphone and iPad. Images that have other profiles are not shown correctly. It shouldn't matter that much that you don't have a calibrated display - the changes in the images as posted are not related to calibration but rather color profile error.
You need to start from the beginning and trace the image to see where the profile was incorrectly applied. Was it a jpg image - shot in which space? When you imported and exported from Aperture, which space did you save it in? Follow the image from beginning to end and you should be able to track the error.-- hide signature --
Yes, in the end it is exactly what you said. My camera is just shooting JPEGS in sRGB, but I used a NIK plugin which saves the files as TIFF with AdobeRGB. I just dragged the photo to the desktop, which kept the profile in place. Thanks!