Loc = MP.ActiveMap.GetLocation(Lat, Lon, Alt);
    Shape s = MP.ActiveMap.Shapes.AddShape(GeoAutoShapeType.geoShapeRadius, Loc, 100, 100);
    s.Line.Weight = 0;
    s.Select();
    object o = 1;
    Recordset rs = MP.ActiveMap.DataSets.get_Item(ref o).QueryShape(s);
    rs.MoveFirst();
    while (!rs.EOF) {
        // here we have all pushpins
        rs.MoveNext();
    }

    MapPoint.DataSet InCircle = MP.ActiveMap.DataSets.AddPushpinSet("In circle");
    rs.MoveFirst();
    while (!rs.EOF) {
        rs.Pushpin.MoveTo(InCircle);
        rs.MoveNext();
    }
    o = "In circle";
    rs = MP.ActiveMap.DataSets.get_Item(ref o).QueryShape(s);
    rs.MoveFirst();
    while (!rs.EOF) {
        // here we have all pushpins
        rs.MoveNext();
    }