Homogenised milk

[Panic Button]

Just what do they do to stop the cream rising to the top?

[Clanad]

The raw milk is forced, under high pressure through an orfice (kind of a screen like affair) which causes the fat globules to be much smaller than normal. Because the surface area is decreased they have less of a tendency to seperate from the skim milk and float to the top...

[heathfield]

It's the same process as when you make a salad dressing by whipping oil and water in a blender. The oil globules become so small that they can't coalesce.
Good description here.