Depends what you mean by 'not in order'
Neither parallelism, nor multiple tempDB files are going to result in a query with an order by returning data out of order. Any time there's a query without an order by, no order is ever guaranteed and hence no order should ever be assumed, no matter what the server setup is.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability