The current version of the GNOME desktop is 2.24. GNOME releases happen predictably every six months; the current development timeline calls for the 2.26 release to happen on March 18, 2009. The GNOME project usually sticks quite close to its schedules.
Predicting what will be in that release can be challenging; most development in GNOME is happening with individual modules and one only knows what will be accomplished when all of those modules come together for release. Some hints can be found in the GNOME roadmap, though. There is occasional talk of GNOME 3.0, which would be a major, binary-incompatible release, but no movement in that direction at this time.
The current KDE release is 4.2.0. With this release, the KDE development community hopes to shake off some of the "not yet ready" complaints which have followed the 4.0 release. By all accounts, things are getting better, and 4.2.0 is the best KDE 4.x release yet. Some users still complain of bugs and missing features, though.
The GNU Compiler Collection is currently at version 4.3.3, released on January 24, 2009. This release includes a number of optimizer improvements, experimental C++0x support, improved Fortran 2003 support, better Java compilation (using the Eclipse Java compiler), and more; see the 4.3.0 changes file for the full list.
Glibc is the GNU C library, the lowest-level system library which interfaces directly with the kernel. Several libc implementations exist, but glibc is the version shipped with most distributions; it is used almost everywhere except in some embedded Linux deployments. The current glibc release is 2.6.1. There is a 2.7 release in the works with no planned release date; expected features include better fortification (protection against some security exploits) for C++, better cpuset support, support for the new O_CLOEXEC flag, x86_64 vDSO support, and more.
It is worth noting that glibc is likely to transition to version 3 of the GNU Lesser General Public License sometime in the relatively near future. Most users and developers should not notice this change, but it could be relevant for vendors who package glibc into devices where it cannot be replaced by end users.
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