From GopherCon website:

GopherCon 2015 will take place in Denver, Colorado on July 7th through July 10th, 2015. We will be accepting talk proposals from January 20th through March 31st, 2015. Due to the competitive nature of the selection process, we encourage you to submit your proposal as early as possible. GopherCon is a single-track conference with two days of talks. This means that the number of proposals we can accept is limited to the number of talks we can comfortably fit in two days. Don't be disappointed if your proposal isn't accepted!