Record Sharing

Hello Guys,

I'm little bit confused about sharing of records. I have a couple of questions on record sharing in MS CRM

1) Can different Organization share records For ex : Org A and Org B are different Organization. Org A has one Account (say : Jonnathan), is there is a way to share that record to Org B?

2) How can i share records between two different business units which are not fall under same parent BU.

For Ex

Organization

/                    \

BU 1                BU 2

I want to share records between BU1 and BU2