In "The Distraction Addiction", Alex Soojung-Kim Pang reports something on this that surprised me. My initial reaction to the question of modern technology distracting us and making mindfulness hard was to say "absolutely". I agreed (still do to some extent) with Nick Carr in "The Shallows", that the Internet is making us stupid.
But Alex Soojung-Kim Pang talked to several Buddhists who were active on the Internet, including, I believe, our very own @yuttadhammo, and got a reaction of surprise from them on this question. Their overall answer seemed to be, no, of course modern technology is not any more or less distracting than anything else, because distraction is an internal state -- i.e. it is our reaction to the external stimuli that matters, not the external stimuli themselves.
To square that with my own experience of Clear and Present Distraction from e-things, I note that the people he talked to were experienced meditators. So my current theory is that if you have achieved a certain level of advancement in meditation, you may well be able to operate without technology being a problem; but until you have reached that level, distracting modern technology may act as an obstacle to you even reaching that level of advancement.
In summary: newbies should explicitly guard the sense doors -- a.k.a. turn your phone off sometimes!; but advanced meditators may not need to be as cautious (because they implicitly do it anyway).