postgres/oracle replication?

So the company I work for is blindly rushing into a project that would put
Oracle on all of our colocated servers (100+ worldwide), replacing the
current mySQL DB. These servers perform simple SELECT/INSERT/UPDATE
operations - nothing requiring the horsepower that Oracle might provide.

We have a central Oracle database, which we currently use a nightly
replication script on to install onto the colo mySQL sites. The central
Oracle DB will stay regardless of the decision we would make, but I'm
curious if we have any options involving Postgres (or any other Open
Source SQL DB), that would give us a more standardized replication method,
as well as a better centralized management system like the one that Oracle
provides.

Any help would be appreciated!

TIA!
-lev