Our goal is to eventually have full integration between MailChimp and all the major CRMs. It’s why we’ve invested so much into building a robust API.
Our first "baby step" in that direction is our recent integration with Salesforce.com and Highrise (37signals’ CRM product). If you’re a MailChimp user, you can now give us your Salesforce or Highrise information, and we’ll import your customers into a list, so you can send an email campaign to them (and track opens, clicks, etc).
We call this a "baby step" because for now, it’s a one-way conversation. In future releases, we’ll introduce functionality to sync data "both ways." Stay tuned.
Batchbook is an exception to all this. Their CRM is MailChimp-ready right out of the box, so the integration is easy and seamless (check out their demo video here). You can quickly build segments within Batchbook by searching your customer "tags" and "super tags." Then, you pass the list over to MailChimp with the click of a button. MailChimp gives them two opposable thumbs up!