A boxed copy of Mac OS X (Leopard) does not include iLife which needs to be purchased separately. Apple does produce a Mac Box Set which includes Leopard, iLife and iWork.
iLife is included with all new Macs.
Mac OS X 10.6 (Snow Leopard) will not include iLife '09 as this is a separate product. New Macs that come with Snow Leopard installed will have iLife included.
The current version iLife '11 requires Mac OS X 10.6 (Snow Leopard). The previous version iLife '09 requires Mac OS X 10.5.6 or later.
Boxed versions of Mac OS X do not include the iLife suite which is available separately.
The last version of iLife that will run on Macs running Mac OS X 10.3 (Panther) is iLife '05.
iLife 08 requires Mac OS X v10.4.9 or later.
All new Macs are supplied with the latest version of Mac OS X which is currently 10.6 Snow Leopard.
No. iLife '08 requires 10.4.9 or later.
There is, you may need to buy it though.
Mac OS Leopard
A G4 iMac needs to be running at 867MHz or faster with Mac OS X v10.5.6 Leopard to use most of iLife '09.Neither iMovie nor GarageBand's Learn to Play feature will work as they require an Intel-based Mac with a dual-core processor.
Currently, it's $129 dollars (Mac OS X Leopard). Once Snow Leopard is available (August 28), it will be a $30 dollar upgrade from Mac OS X Leopard.
MAC OS X Leopard which it's current version is MAC OS 10.5.8, maybe 10.5.9 in the future if they ever come out with another update for Leopard.