It is probably best to see it as an Object-oriented language, with many ideas borrowed from Eiffel. Even the name is inspired by Eiffel; the Sather Tower is a recognizable landmark at Berkeley. Sather also takes inspiration from other programming languages and paradigms. There are some features normally only found in functional programming languages.
The original Berkeley implementation is now maintained by many people, not all at Berkeley, and has been adopted by the Free Software Foundation. There are at least two other implementations: Sather-K from the University of Karlsruhe, and Sather-W from the University of Waikato.
Sather is implemented as a compiler to C. With optimizations in the C compiler, Sather can perform better than the corresponding C++ code, and the generated C code can always be optimized by hand.
A Hello, world program in Sather is:
class HELLO_WORLD is main is #OUT+"Hello World\\n"; end; end;