Tcl 8.2 is primarily a bug fix and stabilization release. This release is recommended instead of Tcl 8.1.
Tcl 8.2 adds almost no new features at the Tcl script level. Instead, it adds a few new C APIs that enable some interesting extensions to be added without having to modify the core Tcl distribution. At the same time, Scriptics focused on the outstanding bug reports in order to make the 8.2 release as stable as possible.