The new features covered include:

• Fast-loading ELF binaries. Changes to the static and dynamic linker permit load times which are faster than those of statically linked binaries.
• Start-up time improvements for internationalized applications.
• Support for thread-local storage. This requires extensions to the ELF binary format. Everyone using threads will welcome this, and everybody implementing compilers needs to know about it.
• Thread-local locale support. The current locale model is completely inadequate for multi-threaded applications. The new model will change this, and is also required for a complete implementation of the i18n parts of the C++ standard library.
• Better checking for API violations. One reason programs break between glibc upgrades is due to programmers using forbidden interfaces. Some new technology makes it easier to detect this.
• glibc 2.3 will be much better optimized by using techniques which are of interest to and applicable by everyone who writes libraries.

Many more new and important features would be covered briefly.