How to access Google/Gmail/Gchat/Reader user icons

I'm building a Google Reader client and wonder if it's possible to access a user's profile image (aka avatar) directly. When I navigate to the images in Reader itself, I find that they point to URLs such as http://www.google.com/s2/photos/private/AIbEiAIAAABDCPaY2PPrqNnxZiILdmNhcmRfcGhvdG8qKDE3开发者_开发技巧NTc5YmI2NzI3YmRjOTcwNDAzMmQxZWJjYzQyZmI3OTZiN2Q2OWIwAWemZGBQZDGn5s12810FVk1rR3vd

Which as far as I can tell doesn't correspond to anything within the reader API.

Any thoughts welcome! Thanks!

I don't know much about the Reader API (there's no official one, is there?) but if you have the contact's email address you can use the Contacts API to retrieve a photo for that contact.