Scott Guthrie's blog about how they intended to do it.
This appears to do nothing:
{{link fieldname}}
This appears to blow up:
${link fieldname}
Any ideas?
He prefaces the section and example code with the following:
Currently, we are working on an extension of the data linking proposal to support declarative data linking.
It's a planned extension/feature, but it's not in the first go-around.