The decision was taken at the GNOME Users' and Developers' European Conference which is underway in The Hague, Netherlands, this week.
In a media release, the GNOME desktop project said the release team had met on Monday and, after discussing the progress of the release, decided to put it off by six months.
GNOME has a six-month release schedule; the releases of Ubuntu GNU/Linux are tied to the GNOME release cycle.
The media release said: "While it might be possible to release GNOME 3.0 in 2010 by slipping the schedule by a month or two, it makes more sense to stick to GNOME's release schedule and ensure that GNOME 3.0 lives up to the quality that our community expects."
"The GNOME Project will ship GNOME 2.32 in September, along with a preview release of GNOME 3.0. Several of the distributions will ship GNOME 3.0 components that can be used for user previews or developer testing."
The GNOME project has been under pressure to come out with a snazzy, new look after, KDE, the other commonly used DE for Linux, underwent a massive transformation a few years ago.