OU software direction
The OU seem to be heading towards FOSS solutions at the present. For example the main forum software is currently First Class ( http://www.firstclass.com/ ), which is being moved to Moodle ( http://moodle.org/ ) during the next year. Also a friend has recently completed 'S194 Introducing Astronomy' in which the FOSS application Stellarium ( http://www.stellarium.org/ ) was used as part of the course software.
Another point worth noting is that the OU's new Vice Chancellor is Martin Bean, who was General Manager within the Education Products Group at Microsoft, as well as having worked at Novell amongst others. ( http://www.open.ac.uk/about/organise/ ) So it seems that it could go either way at this stage.
Disclosure: I am a current OU student.