Multiple Contacts on Accounts, Sales Orders, Invoices etc

Multiple Contacts on Accounts, Sales Orders, Invoices etc

Hi Guys,
I understand that N:N relationships between Contacts and Accounts, Sales Invoices etc. is not supported. This is important as CRM needs to be able to track people as they move from account to account (people changing jobs etc.) Can you tell when this will be implemented? Also multiple Contacts are needed on Sales Orders and Invoices.

Thanks
Andrew