Typical process, started with a 30 minute phone screen. The following week I came in for 4 hours to talk to 5 people.
Most conversations were white board and technical; algorithm, testing, & design. If you're already practicing you'll be fine.
I am dissatisfied with my overall experience, it seemed one sided. LiquidPlanner was aggressive on getting me in. They did not leave time in-between conversations, so a bathroom or water break meant I didn't have time for questions. The odd thing is they scheduled over the lunch period and didn't provide one.
I wouldn't discourage anyone from interviewing as I met some great people. I would encourage you to negotiate and find out how they treat someone who has boundaries.