Spain's high-speed rail service, the AVE, continues its expansion over the country with a new service from Seville to Valencia, with stops in Cordoba and Cuenca along the way. Now you can get from Seville to Valencia in under four hours, from city to center to city center, without the hassle of checking your bags or transfering from airport to city. The journey from Cordoba to Cuenca is just two hours. There are currently some special offers for this new service on the RENFE website.
No new rails have been laid down for this service. Instead, it appears to use the existing Madrid to Seville and Madrid to Valencia lines (though this service doesn't actually stop in Madrid). A similar thing was done recently when they connected Barcelona to Malaga by AVE train.