Well, this is something quite neat.
I needed to give users the ability to select items from a list of 78000 items.....
I was thinking about the best way to do this and came up with the following idea and it would seem that InfoPath is perhaps a bit more clever than I have previously given it credit for :-)

 

On the main form view have a textbox and place a button next to it which switches the view to your "list view", on this list view place the results from the web service/data connection in a nice repeating table. On each row then add a button which sets the textbox on the orginal screen to contain the value chosen on this screen (InfoPath automatically picks the line where the button is!) and then switch views back to the main form view again.

 

This is some really neat functionality, I will be adding functionality to my list view so that the user can filter the list so that not all 78000 items are shown at once! I am quite happy about this. Well Done InfoPath dev team, this is sweet!