Colin Bird said when you scale it's even more important to understand the principles (of the Agile Manifesto). Damn right! So often they're compromised and you end up with something that just isn't that agile anymore. The practices also need to be consistent across the organisation.
Here's what I took from the session:
Start off with a beach-head team to build a head of steam. Create a cross-functional team from early evangelists and opinion leaders. Keep the team together long enough to succeed. Start small and make the team progressively larger over time, until it eventually becomes too big. Then split out people to seed new teams.
Create enough cause for people in different teams to talk to one another. If you cannot avoid distributed teams, maximise communication with instant messengers and VOIP solutions; use an integrated development environment with a common continuous integration environment; cycle people through all teams.
Avoid communities of common disciplines, e.g. DBAs or architects.
Stagger daily stand-ups so that people from other teams can attend.
Synchronise iterations to allow joint planning and delivery.