Hi Soumya
The Task TS000007869, is it stand alone - triggered directly by an application or is part of a workflow in your system?
If it's a standalone, not much can be done as you would need to do some coding for your requirement.
If it's a part of the workflow, you can create a virtual attribute in the base BO, in the coding of which would read the description, extract the PO, get the GR, if found set the attribute value to YES. Then set the dynamic columns (see link: Create Dynamic Columns - Wiki - SCN Wiki ) . Whenever the list is refreshed, the virtual attributes are recalculated and would let the users know the GR status.
However, there can be a performance impact as this will happen for all workitems of that Task.
also, the column names will be displayed with the header specified in the configuration SWL1 only when all the work items in the inbox belong to the same task. Otherwise, it will use ‘Dynamic Column’ as the header of the column.
Also see if you can use BADI WF_BWP_DYN_COLUMN ...some points can be picked up from SCN thread: http://scn.sap.com/thread/2007514
Regards,
Modak