Database Replication?

xcaster asks: "I've been working with Lotus Notes for several years. Although Lotus Notes is horrible software, it wins in one feature: replication. I've researching all major RDBMS for a while, and found that even though they offer replication support, none provides easy-to-use, flexible support for disconnected-user-oriented replication. Do real solutions for replication for disconnected users exist out there?" It would be interesting to see how well the major free RDBMS engines stack up when it comes to replication. Which RDBMS software can support replication out of the box, and for the ones that do not, what changes would they need to make to support it?