A new version of the API (v4) is available here: developers.linode.com.

Volume Methods

This family of API methods allows you to manage your existing block storage volumes or easily create and attach new ones. For example, creating a volume is as simple as:

volume.create(DatacenterID, Size, Label)

This would automatically create a new block storage volume in the datacenter of your choosing, using the indicated size. The new volume's ID is returned so you can use the other API methods to resize, attach, or detach the new volume.