At the moment end-users should not be installing MeeGo on the n900.

Maemo 5 is the currently supported platform. It's fully functioning (depending on your point-of-view).

The 1.2 update will include QT which aligns Maemo 5 closer to MeeGo.

MeeGo on the n900 will take many months before it can be fully functioning.
During that time it is in "development" - nobody should be installing it until it is ready for daily use.

If an end-user installs the "development" version and expecting full functionality then that user has been mis-informed.

Maemo 5 is the current OS of the n900.
Developers are still writing software for it. The repos are growing on daily basis.