It's possible to get to Penne by flying to Rome from almost anywhere and then getting the train to Pescara, but it makes for a long day's travelling. The quickest way is to fly direct to Pescara, about 40 minutes drive from Penne. Apart from connections within Italy, there are flights to Pescara from most of Italy and now JFK in New York and Toronto too. Pescara airport has an English-language timetable.
Direct flights to Pescara from the UK are all run by Ryanair from Stansted. Depending on the time of year the number of flights varies from two a week (Thursday and Saturday in 2006) between October and January to one a day in the summer. Book the flights from the Ryanair website; prices vary between 35p each way (plus taxes etc) and £40. Prices tend to go up sharply just before the flight date.
There is a taxi stand outside the airport; a direct ride to Penne costs around 40 euros. There is also a bus stop; all buses from here go to Pescara train station. There is another bus which runs from the train station to Penne once an hour; the bus journey from the airport to Penne takes about 90 minutes in total. But the easiest and most flexible way to travel is to hire a car from the airport (which has stands for Avis, Sixt, Hertz, Maggiore and Europcar) and drive to Penne.