I've recently noticed a few discussions (one thread is in the FIM 2010 forum) on how to get pictures loaded into FIM and maybe into Active Directory (AD); for a recent customer project I did a VERY quick Extensible Management Agent (ECMA) with an extension to load pictures from a file share and into to FIM.
I want to strees that this ECMA has not been extensively tested for production and is missing some error handling and good logging. But it is currently running a burn-in at customer site and seems to be working properly, so if it will help you go in the right direction - well, then it is all yours for inspiration.
The current version basically loads JPG files from a file share specified as a Config Parameter and turns the pictures into a Base64 string. The Extension then actually converts the string back to a byte array which can be directly exported to Active Directory thumbnailPhoto.
Remember that the general recommendation is to store pictures in Active Directory at a size of 96x96 pixels and a size of less than 10Kb; however, I have heard from Microsoft that the attribute thumbnailPhoto actually supports up to 100Kb size pictures, so you'd would have to check with the different applications for size and dimensions expectations, i.e. Outlook enjoys a 96x96 picture but other application may have other preferences and SharePoint generates three different size, 144x144, 96x96 and 32x32 pixels for use in different situations.
Get the compiled version and source code for both the XMA and the Extension here.