Clear sepertion between a task's duration (how much time will the task take) 
and the effort for a resource. E.g. the shipment of a parcel takes 5 days but 
my effort for tracking etc is just 2 hours. This function is not provided to 
many project management tools.

PMBOK is not a methodology, so one can't "follow the steps" as such. Perhaps it
would be better to specify at any point in time which aspects of the PMBOK the
current OOPM implements - or use the PMBOK as a roadmap for explaining the
development of the OOPM to project managers.

This request simply doesn't make sense as kwest pointed out.  However, I would
strongly advise against put anything in the product that tightly couples it to
PMBOK.  The PMBOK will change and you don't want PMI causing your product to be
out of date.  Also, realize that PMBOK is *not* the be-all and end-all of
project management.  There are real methodologies and other approaches that will
come into favor.  Perhaps you could take some vocabulary from PMBOK, and maybe
use its concepts in the help or documentation (?) for the product.  But that's
as far as it should go.

Should we then close this requirement?

Close it.

Maybe a PMBOK 'template' option (plus a PRINCE2 one and any others that can be 
added for that matter). Tying the app to any one approach or methodology would 
be counter-productive, but out-of-the-box support for established methods would 
be a good thing.

I agree with pwheel, bulding the tool around PMBOK would not be sensible. 
Perhaps some sort of method plugin option should be avilable upon project 
creation (PMBOK, Prince2, ITIL) which will shape how the project is defined 
within the application.

I will create some derived whishes/criterias and close this one.

- Support for different project methods which can be selected when creating a
project (examples: PMBOK, Prince2, ITIL ...)
- Separate task duration and ressource effort

"Support for different project management methods" is now issue 99317 and

"Separate task duration and ressource effort" is now issue 99321.

Closing this task as WONTFIX because it can't be done - see comments above.

wontfix -> closed

Although this issue is CLOSED, I recommend considering the following:

Project Management (PMBOK, PRINCE2, etc.) propose "Deliverables" that are 
recommended dependent on situations or expectations for a given project.  These 
deliverables could be used to create a "OOPM Template" that gives each Project 
Manager a targeted End POint for a segment of their project schedule without 
pre-defining the tasks necessary to achieve that "Deliverable", nor does this 
template mandate that each section and subsection of these templated 
deliverables are needed for each project.

System Development Life Cycles (SDLCs) like MERISE, Agile / Scrum, Software 
ENgineering and Object Oriented published materials also 
recommend "Deliverables" when following their processes.  And, THESE 
deliverables are also premised on the expected Scope and Objectives of each 
project.  Templates of these Deliverables could also be made available to 
Project Managers for use similar to the PMLC artifacts above.