This release is the first one with a new design of ECL, which includes changes in the way streams are implemented, support for full Unicode character set, safety against interrupts and serious performance improvements.
Please read the changelog http://common-lisp.net/cgi-bin/viewcvs.cgi/ecl/src/CHANGELOG?root=ecl&view=markup to get a feeling of the many fixes and improvements.
In particular I want to remark the new module, BYTECMP, which implements bytecodes compilations. By configuring this module as a built-in part of ECL (--with-bytecmp=builtin) you will be able to ship ECL to places that lack a C compiler, while still being able to use COMPILE and COMPILE-FILE.
Further information and links to the download mirrors, at http://ecls.sourceforge.net