One exception that I'm aware of is an iOS and Android app called Jibbigo, which offers free language translation with a connection. But for $4.99 per "language pair," they'll let you download their "offline translator." (Unfortunately for me, Jibbigo doesn't support Turkish.)
The other good news is that the revolution in travel apps includes sign-reading apps that don't require an Internet connection.
For example, apps like Pleco (for translation of Chinese into English) and Word Lens (for English to and from French, Italian or Spanish) will translate written words, so you can "read" menus and signs without an Internet connection.
Another potentially awesome resource for travelers originates in the same research organization as Apple's artificial intelligence voice assistant, Siri.
Currently in a public beta release, the iPad-only app is called Desti, and it uses Siri-like natural language processing and semantic search to "understand" and then answer questions you have when you're traveling.
With Desti, a new iPad app now in public beta, users type in questions in natural language and get back advice about where to stay, what to eat and what to do while traveling.
The Desti service "harvests" information from social networks about the details that people have uploaded about hotels, restaurants and other places you may visit. Plus, it draws information from Factual, Wikipedia, Foursquare and a database used by Hotels Combined.
You type in natural-language questions, such as "where can I find a nice hotel with a comfortable bed?"
The results are presented on a card with pictures.
The app could be amazing for international travelers -- it's just the kind of thing you need to fully enjoy a foreign country. Right now, it's limited to Northern California. The drawback is that if it goes international, you won't be able to use it while traveling abroad unless you pay a fortune for broadband data roaming.
(By the way, Siri is useless without a connection, too.)
How bad is the connection problem?