Ubuntu CTO Matt Zimmerman has announced two Ubuntu Technical Board decisions that will affect the upcoming Feisty Fawn release, due out in April of this year. For the Feisty release, proprietary video drivers are out of the default install, and the PowerPC port of Ubuntu is being downgraded to an unofficial release.
According to the release, Feisty will "preserve the status quo with respect to proprietary video drivers." This doesn't mean that Ubuntu will be completely clean of proprietary software.
Additionally, a team has been formed to work on the PowerPC, and if community support for the port is strong enough, there's no reason Ubuntu won't continue to be perfectly usable for PowerPC owners, even in its "unofficial" status.