Some of the WSS 3.0/MOSS API's which fires the query SELECT TOP 2147483648
§ list.Items.XmlDataSchema
§ list.Items.Xml
§ list.Items.QueryFieldNames
§ list.Items.NumberOfFields
§ list.Items.ListItemCollectionPosition
§ list.Items.Count
§ list.Items.GetDataTable()
§ list.Items.GetItemById(40)
§ list.Items.ReorderItems()
§ list.Items.Delete(40)
§ list.Items.DeleteById(40)
SPQuery without RowLimit property set would fire the same the query.
I have not listed all the API calls which would fire the above query.