There is. I use the gpSPhone. I checked the link that Mupen64 Man give. It says you need to give $5 for it but mine is free. I just downloaded via the Cydia.
The only problem is you can't save more than one save file for a game like in VBA for PC. In VBA, everyone in your family play and save with respective save file names(and different profiles, ofcourse). gpSPhone does save with different file name(only the number which indicates date,day and time changed) when you press save in new file but you can't change the file name as you like so that leads to the same logic as you can't save more than one save file.