Lancelot is an ALI (application launcher interface) for KDE 4 designed to provide a place from which all your jobs begin. It provides quick access to applications, places, documents, contacts and system information.
It is a part of KDE since 4.2, so you should have it in your distribution's package repository. It should be in kdeplasma-addons package.
PLEASE READ BEFORE COMMENTING:
[size=1]I almost *never* check the comments here[/size]
For questions and comments, use KDE forums or find me (nickname: ivan|***) on #plasma channel on freenode.
For reporting bugs, go to http://bugs.kde.org/
For requesting new features, visit http://forum.kde.org/showthread.php?tid=15049