accessing data from other databases?

I have two separate (postgres) databases each of which contain a set of
tables with the same names. Now it turns out that one of the tables between
these two databases can be shared. What's my best way of proceeding? I was
hoping that I could just access this table from either database, but when I
try to do so I get the error:

ERROR:   cross-database references are not implemented...

I'd rather not combine the databases, since they are huge, and apart from
this one table which is relevant to both, they are quite independent. I'm
also not keen on maintaining two copies of the one table which is relevant to
both, since it will change with time. Are there any other options?

Thanks for any suggestions,
Celia McInnis