I am currently writing a modified Tiny core for the Tiny84/44/24, Tiny85/45/25, and Tiny2313 chips with to goal to bring the existing core closer to Arduino.
Current changes include:
-Removed the core_*** files and made everything configurable through just the Pins_Arduino.h file, with each variant having its own folder as with the normal arduino core.
-Removed the use of Macros to generate function names which should maje it alot easier to add new variants to the core.
-Replaced TinyDebugSerial with a new class I have written which allows attiny's with no hardware UART to have an equivalent software version using pin change interrupts.
-Updated Print.h/Print.cpp so that they correctly match Arduino 1.0+
-Planning on adding a software SPI library, though this is not finished yet.
-Removed WProgram.h and transfered code into Arduino.h to match the standard arduino core.
-Replaced the String library with the Teensy version.
Any volunteers for testing. I currently only have an Attiny84 chip, so am looking for people with the other ones listed above. Volunteers need to have experience with debugging, programming the chips etc.
Put your name down here, and I will PM you the core.