I'm working in a product company developing about 20 products and having about 40 developers in staff. Developers are united in teams (5-10 persons), and each team works on a set of products. Each team has more or less freedom (as some products depend on other ones) in choosing duration of sprint. For each sprint team implements a set of features in the products they are working on, but products are released separately, usually on demand.
By now we have a strong need to migrate from self-made issue tracking tool to something more convenient and functional. I looked at JIRA(+Greenhopper) and appreciated it's simplicity and customization opportunities. But I have no idea how we can implement our process with a plain structure of projects and sprints based on releases used in JIRA.