Could be any program.
Cubase, FLStudio, Logic, ACID etc. etc. etc.
The list is endless pretty much. Those are the programs people use to produce the song and put everything together. Good producers have tons of different hardware to get that one sound they're looking for and then import it into their master mixer. An alternative to hardware are VSTi's (pretty much software that tries to mimic what certain hardware does), but they're not the real deal.