I have used mandrill too for the last year. I advise you to use mandrill api for node.js - it is much faster and simplest way to fill emails queue.
With mandrill-api you can send messages in sync/async modes. Async just checks email data and add message in the queue, then immediately call a callback with status (message in queue). Sync - calls callback with a result of sending (but not delivering).
But most powerful thing is mandrill hooks - you can define a few hooks and call your app when email delivered, skipped, bounced, marked as spam. You can even track opens, click, reviews etc. So you can manage messages states and get some analytics data with mandrill-api.
And note that with api you can compose emails with MailChimp using MailChimp Markup Language (or handlebars), then export templates into Mandrill and send templates with array of addresses, merged variables and etc.
Ok, but give me some rest! I’ll get some off-work time to wrap my stuff into the package this weekend. And if you wish I can also write some simple docs or post for this one. But get ready that package will have a few dependencies like meteorhacks:picker and some async stuff