How to - iTunes 9 Genius mixes
Where are Genius Mixes?
To get the Genius Mixes feature to appear, you have to update Genius.
Navigate to Store > Update Genius. Genius Mixes will appear under the regular Genius playlist option.
On the iPhone and iPod touch, you need to have Genius Mixes turned on within iTunes. Plug your iPhone or iPod touch into your computer. Select your iPhone in the left panel and then navigate to the Music tab. There you can check the Genius Mixes under playlists. Those mixes will be synced to your iPhone. Careful, since you can't tell how many songs are in the Genius Mixes, the mix could be more than your device can handle if you have a large music library.
[Via Maclife]