hi,
I also noticed that all the status codes that are set and then get used in the interrupt routine are the same codes with same meanings for both chips!!

Then you will not be surprised with that Atmel`s TWI (two-wire interface) has used the same codes and similar control registers` set too.

It would appear that Philips and Cygnal both purchased the same IP for this peripheral functions on their chips

For me it looks simple: they try to be as much close with the patented I²C specifications as possible. As about names, so SMBus is a trademark of Intel Corp.; I2C is a trademark of Philips Semiconductors, Inc.; TWI - here: just a shortcut from Two Wire Interface.

btw, another info about I²C: http://www.esacademy.com/faq/i2c/

Regards,
Oleg