Yes, it is possible to connect your iPad (or iPhone) for a bargain price to the Cable&Wireless (Movil) 3G cellular network in Panama, but it takes some careful steps. I'll explain how to do it.
Go to the Cable&Wireless central store on Via Espana in Panama City (or maybe any other CW store?). Take your iPad, a cellular phone (you need to send text messages to activate the account) a pair of scissors (you need to trim down the SIM card to a miniSIM) and a paperclip. At the store you buy a SIM card for $1 and a $14,95 data plan for one month (1Gb max).
Data plans for one day cost $1 but don't mix monthly and daily data plans with the same SIM! I tried a one day plan first to see if I could get it to work. It did, but then I had major trouble to change the one-day account into a one month account. What happens then is that after one day your $14,95 credit is eaten fast by hefty data fees and stops... This happened to me twice and only a lot of talking to the friendly girls at CW got my account re-activated, so then buy another 1$ SIM with no one-day-history.
So you got the SIM and the $14,95 monthly plan. Insert the SIM in your cellphone, unlock the SIM and activate the monthly plan with the code *456# talk/send.
Now compare the SIM with the (AT&T) MiniSIM already present in your iPad and trim it to the same size. Insert the MiniSIM in the iPad and unlock it. There is one final important step. In Settings> Cellular Data> APN Settings you fill in at the APN line: apn01.cwpanama.com.pa
No username or password is required. Presto! Your cellular data is activated and you have a month of Internet all over Panama! Enjoy! The same thing goes for your iPhone, but then I would bring another cellphone for texting and incoming calls on your usual cell number. good luck! Martijn Schroevers