It would require a habit change. And GTD facilitates this by giving you the ability to capture. Whenever you come across any link that may be interesting, you can bookmark it (I have a bookmark folder called INBOX for such purposes which I process during my daily processing) and decide what to do with it later. Many times what initially seemed interesting turns out to be somewhat irrelevant (although interesting!), and the second thought allows you to simply delete the bookmarks. For others you can add scanning or reading actions.
Now the real problem is to be aware that one is being dragged away by the links and break the habit. One way I have found helpful is to visualize, say for a few seconds once or twice a day, how you will do it. Visualize for example, that you have seen an interesting link, but you are dragging it to the inbox rather than clicking on it, saying to yourself that right now you are doing something different.
In addition, considering the three types of work namely predefined, as-it-appears, and defining-your-work, twitter is better considered as the third one and include it in processing. Definitely not as-it-appears. Somehow it's in the nature of the internet to distract us all, perhaps because of the sheer volume and connectedness of information.
I got the above visualization idea after listening to the "Making Change Stick" audio from GTDConnect when I used my trial membership. This audio has changed many things for me.
Regards,
Abhay