Nowadays most components of a full identity infrastructure are available as Open Source components - and some even within The ASF: identity repositories, provisioning engines, access management systems. Picking these bricks to realize a solution that will suit the wide-range ever-changing organizations' needs is a real challenge for all system integrators in the Identity & Access Management area. Some real-word use cases and scenarios will be reviewed in this presentation to highlight strengths, flexibility and benefits - but also wicked problems and possible improvements - that Open Source Identity infrastructures can provide to organizations and final users.