Squeak 4.0 released - now under MIT/Apache license - The H Open Source
h-online.com
h-online.com
Pharo is pretty slick, http://www.pharo-project.org/home. And Gilad Bracha of Strongtalk and JVM fame is also doing interesting work with Newspeak, http://newspeaklanguage.org/.
The Blue Book (Smalltalk-80: The Language and its Implementation by Adele Goldberg and David Robson) is quite old but still one of the best book about Smalltalk. You can get it for free in PDF.
Guess I will run out of excuses soon. ;-)