Hi,
as far as I know 32 bit analysis services has a 3GB limit
on memory.
Yukon, the next SQL-Server will be out in a 64 bit
version accompanied with a 64 bit analysis server.

According to Microsoft, there is no 3GB limit with the 64
bit version.

You might want to read the thread

"Annoucement: Analysis Services Performance Guide Posted
on Technet" a little further down

HTH

Lutz