So I have to say I will admit that students today don't seem to have the same level of focus as generations past. I say don't seem because really I don't think any of us 'educated' graduates can really remember how distractable we were or how 'deeply' we thought about the topics presented to us. I have a feeling that maybe we were just as distractable and shallow.
Regardless, I'm not sure if the internet can be blammed for loss of focus - there are numerous distractions imposed on students today including television, magasines, ipods, mp3's and of course the one that has always been around - teens tend to be distracted by each other.
In addition I would argue that students today have a far greater amount of cursury knowledge over their contemporaries. Today if a student has their interest 'peaked' they can quickly locate information and move along to other topics that are related! Thats not being distracted - that's connecting different topics and making real connections! Regardless, even if students are not delving as deeply into content on the internet - then it's up to teachers to encourage and teach students to develope those skills. If students can be taught to reflect on what they read AND they have the access to information that the internet provides then I think it's obvious that society will benefit.