I just found this complete example project. It shows how to get the integrity label of a file/folder in Windows Vista.
Get Vista integrity label source.

program IL;  

{$APPTYPE CONSOLE}  

uses
  Dialogs,
  JwaVista,
  jwaWindows,
  JwsclSecureObjects,
  JwsclDescriptor,
  JwsclMapping,
  JwsclAcl,
  JwsclTypes,
  SysUtils;  

var Path : String;
    IsDir : Boolean;
    SD : TJwSecurityDescriptor;  

    H : HANDLE;
begin
  Path := ParamStr(1);
  if not FileExists(Path) and not DirectoryExists(Path) then
    exit;  

  IsDir := not FileExists(Path) and DirectoryExists(Path);  

  H := CreateFile(
    PChar(Path),//LPCTSTR lpFileName,
    STANDARD_RIGHTS_READ,//__in          DWORD dwDesiredAccess,
    0,//__in          DWORD dwShareMode,
    nil ,//__in          LPSECURITY_ATTRIBUTES lpSecurityAttributes,
    OPEN_EXISTING,//__in          DWORD dwCreationDisposition,
    FILE_FLAG_BACKUP_SEMANTICS,//__in          DWORD dwFlagsAndAttributes,
    0//__in          HANDLE hTemplateFile
  );  

  if H = INVALID_HANDLE_VALUE then
    RaiseLastOSError;  

  try
    {We could also directly use GetNamedSecurityInfo}
    SD := TJwSecureGeneralObject.GetSecurityInfo(H,SE_FILE_OBJECT,
       [siDaclSecurityInformation,siLabelSecurityInformation]);  

    if Assigned(SD) then
    begin
      if IsDir then
        Writeln(SD.DACL.GetTextMap(TJwSecurityFileFolderMapping))
      else
        Writeln(SD.DACL.GetTextMap(TJwSecurityFileMapping));
    end;  

    if SD.AuditACL.HasMandatoryLabel then
      Writeln(SD.AuditACL.MandatoryLabel.SID.GetText);  

    SD.Free;
  except
    On E : Exception do
      Writeln(E.Message);  

  end;  

  CloseHandle(H);  

  Writeln;
  writeln(‘[Hit return]‘);
  readln;
end.

There is also a second way to get the integrity label.

program MandatoryLabel;

{$APPTYPE CONSOLE}

uses
  JwaWindows, JwaVista, JwsclSecureObjects, JwsclACL, JwsclTypes;

var F : TJwSecureFileObject;
    aLabel : TJwSystemMandatoryAccessControlEntry;
begin
  F := TJwSecureFileObject.Create(‘C:\’);
  try
    aLabel := F.GetMandatoryLabel;
    if Assigned(aLabel) then
    begin
      Writeln(aLabel.GetText());
      if aLabel.GetMandatoryLevelType = MandatoryLevelHigh then
        writeln(‘High integrity level’);
      aLabel.Free;
    end;
  finally
    F.Free;
  end;
end.