Ah, progress. Had telephones existed in Verona of old, Romeo and Juliet would've been able to synchronize their plans perfectly and avoid all that mistaken suicide business. Consider the movie, It's A Wonderful Life: if security cameras had been mounted in the Bedford Falls Building and Loan, George Bailey and his scatterbrained Uncle Billy would've known in a matter of hours what became of the missing $8,000, and Clarence the apprentice angel would've had to find another way to earn his wings. Underwater radar and GPS technologies could've reduced Moby Dick to a short story. My point is, changes in technology and social norms can eliminate certain kinds of problems and conflicts, create previously unforeseen problems and conflicts, and more generally affect the way people behave.
Many writers and authors are jumping into the indie fray these days, dusting off old manuscripts and shorts that have yet to find a home with a traditional publisher, giving them a cursory once-over and forging ahead with indie publication. I applaud these efforts, and hope they continue. But a word of warning: that pre-publication once-over needs to a be a bit more thorough if your material is contemporary, but more than a few years old.
If your upper-middle-class dad gets lost when he hits the road in his brand-new SUV, the reader will be wondering why he doesn't just use his car's (or phone's) GPS to get back on track. Similarly, if your characters' pop culture references include The Oprah Winfrey Show and the post-divorce exploits of Lady Di, those references are dated and the reader will notice.
You may think, "So what if the reader becomes aware at some point that the book was written years ago; it's not like they're going to stop reading it, or think it's a bad book just because of that." I don't disagree, but with all the distractions of the modern world's wonderland of electronics, technology, social media and noise of all kinds, it's already a big enough challenge to get and keep your reader's attention. Anything that takes the reader out of your story world for any reason is to be avoided, even if it's only for the moment or two it takes the reader to mentally observe, "Nobody uses Thomas Guide road map books anymore; this story must've been written a long time ago." Far worse for the reader is the supposedly contemporary story in which the central conflict or source of tension would be easily eliminated with some modern (and common) convenience or other, like caller ID or the internet.
However, stale-dated prose doesn't necessarily require an extensive rewrite. It just calls for the author to manage reader expectations. The simplest fix is to insert subtle cues and signposts in the beginning pages that will let the reader know your story takes place in the recent past. This may be as simple as editing to highlight the anachronisms, rather than merely observing them in passing. If you make a point of the fact that your protagonist works in the Twin Towers in New York, the reader will immediately know the story must take place prior to 9/11/2001 and therefore won't expect to find anything that happened, was invented, or was popularized after that year.
Stories that were intended to be of-the-moment when they were written will probably require a more extensive edit to update or eliminate dated references. For example, your story about the impending doom of Y2K will no longer work as the straightforward thriller you had in mind when you wrote it. You can either take it in the direction of satire or comedy, or change the threat to something people are still worried about today: 2012, anyone?
Finally, don't lose sight of editorial repercussions. If you decide to change your protagonist's paranoia about Y2K to paranoia about 2012 for example, make sure you update all such references throughout the manuscript to maintain consistency.