creating instances in another linode data center

Yes You Can!

Click the "Add a Linode" link (I forget the exact verbiage) on that first screen you get after login where you are presented with a list of your Linodes… after you pick the plan and the billing magic happens, you get to select a datacenter.

Also not a bad idea to check http://www.linode.com/avail.cfm for availability first… it's usually all good, though.