How to do effective business object modeling?

 According to me, object modeling mainly requires the involvement of the domain experts like, people who know the business thoroughly, and who can either make decisions about it or get an answer from someone else who can. Modeling sessions with these people, who are curious, and well informed, can easily digress into side issues ranging from marketing strategies to database reports. Gathering that kind of information is important, but in its own time and place. Conceptual planning for a business goes through phases like why, what, and how.  So planning for business is very important for object modeling.

I agree with ashish on his idea, but then the object modeling succeeds mainly because it focuses on the domain objects and then forces everyone in the group to take the object's viewpoint, and believe me  putting people into the same viewpoint is very difficult, but it is a powerful technique for gaining a group consensus. By contrast, building scenarios around users compels every participant to consider the system from his own personal viewpoint, and how he wants it to work. So having common viewpoint is very important.