There have been a number of blog posts related to Kevin Kelly's great e-book entitled "True Films": http://kk.org/cooltools/archives/002538.php . Those posts also talk about a network connection dialog that sometimes appears when opening a PDF. I thought it would be helpful to clarify exactly what this dialog is and under what conditions it will appear:
1) The network connection dialog, similar to other Trust Manager dialogs, will ask the user if they will allow a connection to be made to the network. This is the same dialog that you might see if you were to click on a URL hyperlink from within the PDF contents. Because Reader is a client application and it does not assume you want to connect online, this dialog is a means to inform users that the connection will take place.
2) This dialog will only appear when you are reading the PDF from within the Reader or Acrobat application.
3) This dialog will not appear when you download a PDF from a website and view it "in-browser" - meaning the PDF is opened using the browser's plug-in for Reader. The reason it doesn't appear is because the user is already connected online to the internet. Our data shows that users read PDF content in-browser a majority of the time as opposed to within the client.
I have read a number of posts that portray this dialog as being a huge hurdle for the business. However, if the dialog doesn't even appear for most users, then I don't forsee this as an issue. Of course, in the end, time will tell.
I hope this information helps clarify a few things and, at minimum, gives you the correct facts to formulate your own opinion. Thanks for the continued feedback in the blogosphere.