PyS60 provides an application user interface layer, which applications can leverage to reduce code size and easily interact with users, as the appuifw module. The development environment makes it really easy to test code on a real device rather than in an emulator.
While the whole standard library isn't present a useful set is provided, and many pure Python standard library modules can be added and will run wihtout change.
Specific libraries offer telephone-based functionality such as
image = camera.take.photo()You can manipulate your contacts and calendar easily from Python.
The PDIS team have added many libraries, and Nick Burch has built a webbrowser.py.
Earlier applications tended to be quick hacks, but the more recent batch of applications are really polished. Traffic cam viewing, stock quote grabbing dictionary lookup and weather display were among those mentioned.
Installation sounds really easy.
The S60 world is excited about Nokia's recent release of the Python implementation as open source, and applications are rapidly getting more mature, with an active community pushing the technology forward. Lots of sample code is available online.
Slides for the talk are available at http://postneo.com/talks/pycon2006/