Gmail/Yahoo/Hotmail email inviting a la Facebook and Myspace. Anyone know how?

I’m looking to build a function into my new social network in which new users can invite their friends to the network via gmail/yahoo/hotmail importer like Myspace and Facebook do. I have looked around for a solution but have only found this:

Does anyone know how or if there are better services?

Thank you.

I don’t specifically know, I’d start here:

Ah okay, thank you. Do you know how to with gmail specifically? I appreciate the input.

Basically you’d have to go to each email provider and find their API which allows you to access their contact list. It’s different for each provider.