I don't think there'd be any problems with panoramic images on Zazzle, although obviously they will fit some products better than others.

I suppose the main problem with piecing lots of images together into one long image is it could end up quite a large file, which could be a problem on some systems or with a slow connection.

Of course one doesn't necessarily have to use each image at it's full original resolution.

I suppose it depends what products one wants to put the panoramic images onto, but given one is going to end up with a fair amount of white space on products such as cards, postcards and mouse pads etc, one doesn't necessarily need the individual images to be of the highest resolution in terms of mega pixels

In fact e.g. my old Olympus 960z 1.3 mp digital camera would be perfectly adequate for smaller panoramic images, because if the resulting images are going to be less than 3ins high even a 1.3mp camera is capable of producing panoramic images in excess of 300 dpi. So in theory one doesn't necessarily need a fantastic digital camera to produce panoramic images and even some relatively basic mobile phone cameras should produce perfectly good results

there are long invites and photocards too...bumper stickers coffee mugs...posters can be cropped to that size