This release has three important focuses: performance improvements in various fronts (garbage collection and hash tables), extending the run-process function and important fixes to let ECL work better with Slime. Note however that now at least Slime from last week's CVS is needed and that future versions of Slime will require at least this version of ECL to work.
See file src/CHANGELOG or browse it online
http://ecls.cvs.sourceforge.net/viewvc/ecls/ecl/src/CHANGELOG?view=markup
Downloading ECL: http://ecls.sf.net/download.html