According to http://quanta.kdewebdev.org/releases.php , the last Quanta release is on KDE3.5.9 (2008-02-20)

What is the replacement of Quanta in KDE4 ?

Thanks.

Unfortunately Quanta is still not ready for KDE4 (as in not finished). It's still lacking manpower. Also, it is heavily based on the kdevplatform, what makes it another dependency in the development chain.

But i wouldn't call it dead. It's just still sadly missing (and i miss it much...).

Quanta is may be planned for KDE5.
A solution has to be identified for people who plan to migrate from KDE3 to KDE4.

EDIT: Amaya [ http://www.w3.org/Amaya/ ] seems to be a good replacement of Quanta.