Two of the major components that will be part of the GNOME 3.0 desktop are GNOME Shell and Zeitgeist. The GNOME Shell redefines the GNOME desktop by taking over the responsibilities of the GNOME Panel in GNOME 2.xx along with the role of the window manager (and it also supports Clutter for making a nice, attractive user-experience). Zeitgeist in the simplest form is an event logging framework to help users find files and other user activity events in a structured way. Unfortunately, both Zeitgeist and the GNOME Shell are running behind schedule and will likely not be ready for GNOME 2.30.
Red Hat's Owen Taylor provided a status update on GNOME Shell where he shares that the shell is usable, but only a beta quality release would potentially be ready before April. Messaging and application browsing are the two key areas still need to be tackled with the GNOME Shell followed by document browsing, accessibility, and internationalization work.
Following Owen's message, Mikkel Kamstrup Erlandsen chimed in with a Zeitgeist status update. Zeitgeist has made a lot of headway and already sports some impressive capabilities, but Mikkel feels that Zeitgeist by March could be possible, though it would be pushing it and cutting corners. Mikkel eludes to a later release being the better option, at least from his perspective.
GNOME's Vincent Untz has now stated that the release team is getting a better idea now whether GNOME 3.0 should be in March or September of 2010. If it's in September, that means GNOME 3.0 would be GNOME 2.32, while GNOME 2.30 would just be named as-is. No official announcement has been made, but we would bet the release team will push back the GNOME 3.0 release to September.
This may come as a disappointment to those that have been very much looking forward to major improvements on the GNOME desktop, but a six-month set-back won't be too bad if it will lead to a better quality release (especially after judging the initial KDE 4.0 release). Additionally, Canonical for instance was not planning on shipping GNOME 3.0 until Ubuntu 10.10 due to Ubuntu 10.04 being their Long-Term Support release and not wanting to ship a potentially buggy desktop, so many desktop Linux users would not even have encountered the 3.0 release until October of 2010.