The Open Informatics Movement is petitioning governmental funding agencies that are giving bioinformatics research grants to require grant-recipients to release their software under Open Source or Free Software licenses.
The first obvious benefit of mandatory software source release is a speedup of software development. Rather than "reinventing the wheel" by duplicating the work of other software projects, researchers will have a pool of publically developed software to build from.
The longer-term benefit is that the software can be studied and reviewed in the same way as the other parts of scientific research. Software flaws can cause as misleading results in the same way as sloppy protocols or faulty math. Exposing all the scientific process to peer review can only lead to better science.