best example is in _layouts/aclinv.aspx

- this page uses a PeopleEditor control called userPicker

to have a look at the codebehind:

-> open "Microsoft.SharePoint.ApplicationPages.dll" in Lutz Roeder's .NET Reflector
-> Go to "Microsoft.SharePoint.ApplicationPages.AclInv"
-> Check out "public void BtnOK_Click(object sender, EventArgs e);"
this event adds users chosen in the PeopleEditor to a group or direclty grants them permissions.

What it does is:

-> Iterate through this.userPicker.ResolvedEntities, map to an array of SPUserInfo[];
-> Like so:
PickerEntity entity2 = (PickerEntity) this.userPicker.ResolvedEntities[index];
SPUserInfo info = new SPUserInfo();
info.LoginName = entity2.Key;
info.Email = (string) entity2.EntityData[PeopleEditor.PeopleInfo.Email];
info.Name = entity2.DisplayText;
info.Notes = string.Empty;
addUsersInfo[index] = info;
-> then add that to a group like so: this.ReferencedGroups.GetByID(int.Parse(this.DdlGroup.SelectedValue)).Users.AddCollection(addUsersInfo);

I've got some bad news for you, sir.

'Microsoft.SharePoint.WebControls.PeopleEditor.PeopleInfo' is inaccessible due to its protection level.

...and, enumerating the key-value pairs in the EntityData hashtable:
DisplayName = WIN2K3\administrator
SPUserID = 1
PrincipalType = User


Any other ideas on how to recover the e-mail address from a PickerEntity?

See http://www.codeproject.com/KB/sharepoint/PeopleEditorControl.aspx

To get the Email Address use

PickerEntity pckEntity = (PickerEntity)peResponsible.ResolvedEntities[0];
//where peResponsible is a PeopleEditor Control

string email = pckEntity.EntityData["Email"].ToString();

Hope it helps

(pckEntity.EntityData["Email"] only in Active Directory user stores. Joe J)

Using this control inside of an update panel and setting its visibility to off on first load, and then to on based on a postback event causes a javascript error. It also causes the control to no longer function.

Solution: Do not use Visible property. Instead use style="display: none" and on postback set to "display: block";