Is linked servers possible with postgresql?

Hi,

Is it possible to define "linked servers" like in MS-SQL?
Or - is any work going on to implement such feature?
So that using 2 postgresql DB's where one is in dmz and one in production -
the last one has defined the one in dmz as a "linked server" and sql's sent
to the internal DB can do joins between tables in internal DB and DB in dmz?

Reg. WS