In recent project, we have a requirement to populate people picker with current user in InfoPath2010 form. It is quite easy to do it in InfoPath; however it does not quite work as we have expected. In the end, we have to use a combination of InfoPath and list event receiver to complete this task. Here are the steps to set the current user to the additional stakeholder display name in InfoPath.
1. Add a set a field’s value rule to InfoPath Form load event.
2. Set the condition as below
3. Configure the set field value action as below, userName() is a built-in function in InfoPath2010
4. Publish the form, you will see the current user is populated with the current user name as below, however when you click the save, the user does not get saved. I guess this is due to the fact the people-picker control needs to perform a post-back to do some tricks.But we could not force the control to do it in InfoPath2010 for the automatically populated user , therefore we have to write up an list event receiver to set the current user.
5. In you SharePoint solution, add event receiver.
6. Copy the code to as specified to the screenshot
public
override
void ItemAdding(SPItemEventProperties properties)
{
//base.ItemAdding(properties);
string keyStakeholders = “Key_x0020_Stakeholders”; // this has to be the static or internal name , not the display name
string seperator = “;#”;
SPUser user = properties.Web.CurrentUser;
if (string.IsNullOrEmpty(SPHelper.SafeToString(properties.AfterProperties[keyStakeholders])))
{
properties.AfterProperties[keyStakeholders] = seperator + user.ID + seperator + user.Name;
}
else {
SPFieldUserValue fieldValue = SPHelper.GetSPFieldUserValue(SPContext.Current.Web, SPHelper.SafeToString(properties.AfterProperties[keyStakeholders]));
properties.AfterProperties[keyStakeholders] = seperator + fieldValue.LookupId + seperator + fieldValue.LookupValue + seperator + user.ID + seperator + user.Name;
}
}
7. Go to the elements.xml under the new event receiver
8. Change the xml highlighted in yellow
From:
TO
9. Deploy your solution; it will work like a charm. 
References:
How to: Create an Event Receiver for a Specific List Instance
[...] Populate people picker with current user in InfoPath2010 [...]