I was referred by a current employee. I submitted my resume through Tableau's website and heard back from a recruiter pretty quick. My first task was to complete a take home assignment that demonstrated my ability to create 'views' in Tableau Desktop. After I received feedback from that I was invited to come onsite to interview with a couple managers and product consultants. I spoke with 4 people for about a half hour each, and in total spent between 3-4 hours onsite-including talking with the recruiters, and getting a tour. None of the questions were too hard, it was mostly behavioral and conversational. If the interview goes well the last step is to do a product demonstration. I couldn't meet onsite again so I did it by via web conference. This was by far the most intensive part. You really have to study the product because they will try to stump you with questions as you present your demo.
The process was a little segmented, but it is very thorough and it is a good way to prove to both yourself and the company that this is a product/company you are excited about. The recruiters are very helpful and approachable and will give plenty of tips and pointers along the way.