Just tried to deploy new salesforce custom site via Metadata API (ant tool) and also tried Eclipse but target org returns the following message:
The Force.com Site subdomain has not been set in the organization
I have modified Metadata and specified username and unique sub-domain name. Example of Custom Site metadata file is below:
Is it generally possible to create Force.com site via Metadata API - did not find any evidence in documentation.
Also can not find Force.com Site among unsupported components