Testing Update.1
As of build candidate-699, activities are no longer bundled with the core build -- they must be installed separately. This page attempts to describe the motivation for the change, and how to get your activities back.
Motivation
OLPC has many deployments, as well as the G1G1 user community, and can't afford to create a build for each deployment. Instead, OLPC will create a "core build" without activities that allows for easy customization of which resources (activities, content bundles) will be installed alongside it. The mechanism for performing this customization is the Customization key.
I ran olpc-update to an update.1 build; how do I get my activities back?
You can download the G1G1_Activity_Pack, unzip it onto a USB key, and reboot with all four game keys held down at once. Linux will boot and unpack each of the bundles into place.
What's the recommended way to upgrade? =
Using a USB key, you can install both a n.ew core build and an activity pack at the same time; this involves unpacking both the G1G1_Activity_Pack and a Customization key onto the same USB key.
Upgrading an secure/insecure machine
"Secure" machines without developer keys will boot a customization key at startup without any intervention. "Insecure" machines with a developer key installed require all four game keys to be held at boot to boot a customization key.