They gave me a coding challenge with a 15 minute time limit. Since it was so short, I ran out of time. I emailed them and asked for more time but never heard back.

Submitted resume at college career fair and get contacted within a week. First scheduled a phone interview with some entry level algorithm question and javascript question. Then reached by recruiter for an onsite interview with 4 engineers. Nothing hard at all since I answer all questions without any difficulty. The questions focus on web concept, data structure, entry level algorithm (not those dynamic programming or ACM stuff) and front-end technology. For example, find all bugs in a micro webapp. Everyone is super friendly and their office is awesome. Unlike most technical companies in that size, people in yelp are very young and dress much more ... fashion. BTW, They have the best cafe and kitchen of all companies I've interviewed.