.net - Generate All Unique Combinations Of Elements Of A IEnumerable(Of T)?

This question is virtually the same as this SO post, only I'm looking for a VB.NET (.NET 4) solution. I've spun my wheels long enough trying to come up with a generic solution to solving this "power set" problem.

Dim choices As IEnumerable(Of String) = {"Coffee", "Tea", "Milk", "Cookies"}
Dim choiceSets = choices.CombineAll()

I'm looking for choiceSets to be an IEnumerable(Of IEnumerable(Of T)) so that I can do something like:

For each choiceSet in choiceSets
Console.WriteLine(String.Join(", ", choiceSet))
Next

[code]...

As you can see, this is every non-repeating combination from the source IEnumerable(Of T) (which could have 1 to many items in it - this example only had 4), it operates based on the order of the items in the source IEnumerable(Of T), and each item in the list is >= the previous item in terms of number of items in the inner IEnumerable(Of T).

For what it's worth, this is not homework; though it sure does feel like it. EDIT: Updated the example so it does not look like the result is alphabetically sorted, to stress that the source IEnumerable(Of T)'s existing order is used and added a 4th choice to clarify the sorting requirement within each set.