Although the previous generation iPod nano had curved glass (it wasn’t universally loved), the Samsung Nexus S was the first mainstream smartphone with curved glass.  If Digitimes is right, the iPhone 5 may be the second (and likely more popular).

…the latest being circulated around the supply chain in Taiwan is that Apple is going to adopt a curved cover glass for its next generation model, according to industry sources.

That would seem to fly in the face of recent reports that the iPhone 5 would be very similar to the iPhone 4 in appearance.  Digitimes has found what they think is anecdotal evidence.

However, in order to push forward the production of curved glass, Apple reportedly has purchased 200-300 glass cutting machines to be used by glass makers, said the sources.

The glass slicing machines are currently being stored at associated assembly plants and will be brought online once yield rates for the production of curved glass reaches a satisfactory level, the sources revealed.

Although Samsung is a competitor wrapped in lawsuits with Apple, it is also a major supplier and obviously has experience with curved glass screens.