Highlights of Tcl 9.0

• 64-bit Capacity: Data values larger than 2Gb
• Unicode and Encodings: full codepoint range, added encodings, encoding profiles to govern I/O, and more.
• Zip Filesystems: mount zipfiles as filesystems
• Attached Archives: enable starkit-style deployment of apps, with support data in filesystem archives attached to executable or libraries. Build tclsh and wish this way.
• New Notifiers: The central event handling engine in Tcl is now constructed on top of the system calls epoll or kqueue when they are available. The select based implementation also remains for platforms where they are not.
• Many new commands and features

Important Incompatibilities in Tcl 9.0

• Namespace varname resolution: Current namespace, not global.
• I/O malencoding: now raises error by default.
• Tilde (~) in pathnames: no longer interpreted as home directory.
• tcl_precision no longer has effect on number formatting

Highlights of Tk 9.0

• Access to OS facilities: notifications, print, and tray systems
• Scalable Vector Graphics: partial support in images, extensive use to enable scalable widget and theme appearances.
• Images: full access to metadata and alpha channel.
• Platform Features and Conventions: many improvements, including two-finger gesture support where available.