People setting out to sea in the Navy are not going to be as isolated as astronauts, but they'll still be away from their families, friends, and the omnipresent entertainment/information networks civilians take for granted for months at a time. Many people enlisting today -- especially young adults who've spent their whole lives online -- are naturally anxious about separation from their gadgets, which led to some interesting questions for Yahoo! Answers on the subject. The consensus: both the U.S. Navy and the U.K.'s Royal Navy will allow you to bring your laptop, iPod, and other gadgets with you when you ship out -- but you won't be able to connect to the Internet.
A 2009 incident might have given some pause about the wisdom of this policy: the USS Hartford collided with the USS New Orleans in the Straight of Hormuz, and an investigation revealed that, among other lapses, the Hartford's navigator was jamming to his tunes on his iPod at the time. But since the same could have happened with a Walkman or vintage-era transistor radio, perhaps we shouldn't lay the blame entirely at the feet of high tech.
Most Americans, when thinking about soldiers' letters home, probably think of wars from the past: the letters our parents or grandparents sent from Europe or the Pacific during World War II, for instance, or the ones you hear read dramatically aloud in documentaries about the Civil War. Because of their vintage, it seems rather quaint, but when you think about it, the ability to communicate with a soldier in a far-off war was really quite an impressive feat, of logistics if not engineering. In more bygone days, a soldier would leave for a war and not be heard from for years, with his fate perhaps unknown to the people back home.
More than anything else, what's made that sort of letter-writing seem quaint in America's current conflicts is Skype. The now Microsoft-owned company first got traction in allowing cheap international calls, and since the U.S. has many networked computers in war zones, soldiers can communicate back with friends and family back home easily; it's actually cheaper to Skype from Afghanistan than it is to make an ordinary phone call from Germany. The service has provided any number of dramatic connections.