I don't think there is a web service for that.
However, you might consider implementing the audit tables for the projects, task, classifications and key members basic tables.
When you enable the audit table, the system is automatically recording any insert, deletion or update of the base table, along with the time stamp and user details.
Developing a service to read from the audit tables might be easier, and less time consuming.
FND: Record History Enabled is the profile option to get the who columns in OAF page, which was introduced in R12.(12.1.1)
May be you might need to a clear cache or oacore bounce to take the profile option change effect.
In an advanced table.
Within Oracle Application Framework (OAF) pages there are times when a user needs to see who created or updated a record.
This information is generally saved in the "WHO columns" of the database tables that are linked to an OAF page through BC4J Entity Objects (EOs). The standard WHO columns represented are as follows.
* Name of the user who created the row
* Date of creation
* Name of user who updated the row
* Date when row was last updated
Clicking the Record History icon brings up the Record History popup window that displays the WHO column values of the current row.