There were loads of interesting talks and of course it depends on ones personal preferences. I personally found the following talks very interesting, hinting at the continued commoditization and programmability of the infrastructure:

https://fosdem.org/2014/schedule/event/virtiaas05/ - SDN's https://fosdem.org/2014/schedule/event/virtiaas99/ - OSv(cloud/paas operating system) https://fosdem.org/2014/schedule/event/virtiaas11/ - high throughput packet processing OS based on Xen, for replacing expensive middle boxes in the network(firewalls, IDS's etc)