Try something along the lines of

with

set [Product List] As

NONEMPTY(

{[Product].[Product Level 4].[All].Children}

, ([Measures].[Revenue],[Date].[Day].&[20121212])

)

-

NONEMPTY(

{[Product].[Product Level 4].[All].Children}

, ([Measures].[Revenue],[Date].[Day].&[20121201])

)

select [Product List] on rows,

{[Date].[Day].&[20121201],[Date].[Day].&[20121212]} on columns

from [Your Cube]

where ([Measures].[Revenue])

Mack