Arduino 0019 is now available from the download page. Changes include:

• SPI library.
• The Ethernet library has been refactored to use the new SPI library. Existing sketches will need: #include <SPI.h> added to the top of their code. Just select SPI from the Sketch > Import Library menu.
• String class
• A0, A1, etc. aliases for the analog input pins
• shiftIn() function
• Added Arduino Pro 5V and Arduino Fio to the boards menu
• Added control over automatic scrolling and outgoing line endings in the serial monitor

and lots more; see the full list in the release notes.