Unfortunately, integration between Access and Office Live Workspace is not possible today.
But there is a really nice integration between Access 2007 and Office Live Small Business product. You can create an Access 2007 application which stores all its data in linked tables that live on an Office Live Small Business site. These linked tables are available from any computer with an Internet connection. You don't have to worry about firewalls, and you don't have to worry about setting up your own server or paying a separate hosting company to do it for you. By the way, this is all free, too.
One quick caveat: This is not the service to try with your million-row application. If you've got an application with < 2000 rows, performance will be zippy. Much above that and you may run into slow-downs.