Since 7.10 Ubuntu for PowerPC is not available on all Ubuntu mirrors, and is moved into the ports section of the main mirror.

7.10 Gutsy Gibbon

• http://cdimage.ubuntu.com/ports/releases/gutsy/release/

7.04 Feisty Fawn

Desktop, Alternate and Server CD can be downloaded from

• http://cdimage.ubuntu.com/ports/releases/feisty/release/

• ftp://ftp.gnome-db.org/mirror/cdimage.ubuntu.com/ports/releases/7.04/release/

6.10 Edgy Eft, 6.06 Dapper Drake and older versions

These version can be found for PowerPC on all official mirrors

http://www.ubuntu.com/getubuntu/downloadmirrors