Help: How to deliver photos to mobile?

Got this enquiry in from colleague Dan. He’s running a photography service and wants to know how best to send photos to phones for customers.

Here’s his message:

Can you point me at information on how to deliver photos from a website to mobile phones? I have a new photography website, which is very basic at the moment, people have to email me to buy prints or jpegs, but I am working on putting a database behind it which will allow online orders, with paypal, and as part of this I want to offer people the opportunity to buy a version which will be sent direct to their mobile.

His site is http://danshotme.com/.

Can anyone help? I think from memory, iTAGG provide some sort of dynamic photo service for mobiles. Any suggestions?