What are the OO development methods/methodologies/lifecycle.

SSADM goes fine with SDLC but its definitely obsoltete and companies
are shifting to Object orientation. Of course UML is highly in
demand and is a widely accepted standard notational language.
However, there is no fixed OO-life cycle or OO methodology yet. Then
wat lifecycle or methodology does the software development houses
use to produce IS. I am sure that they are definitely not using
functional decomposition, data /process oriented SSADM, but if they
using UML to analyse or design a system, then which lifecycle they
prefer ?

Ajay