As I mentioned in another reply here, I'd suggest you ignore the siren call of "most recent" and just pretend it's five years ago. Use the Squeak by Example book with it's associated version of Squeak to get a basic understanding of the environment and the object system's resources.
If you prefer, there's nothing wrong with trying Pharo or one of the commercial Smalltalks available with free, non-commercial licenses. Indeed, the only variety I'd warn against is GNU Smalltalk, which treats Smalltalk as just another file-oriented member of the GNU toolchain. That approach totally misses what made Smalltalk so revolutionary for its time: a rich environment for interacting with and exploring an object system.
If you prefer, there's nothing wrong with trying Pharo or one of the commercial Smalltalks available with free, non-commercial licenses. Indeed, the only variety I'd warn against is GNU Smalltalk, which treats Smalltalk as just another file-oriented member of the GNU toolchain. That approach totally misses what made Smalltalk so revolutionary for its time: a rich environment for interacting with and exploring an object system.