Why is everybody so quick to try and find a scapegoat for all this? The world of the media moves incredibly quickly and is very cut-throat, so really there's every likelihood that Brooks and Coulsen didn't actually have any idea that this was going on. One of their journos comes to them with news that looks good, do you really think the editor is going to have the time to sit down and work out exactly where it came from? Of course not, so trying to pin all the blame on them without a shred of evidence (that I've seen) is completely unfair. Don't even get me started on the whole anti-Murdoch campaign trying to use this as a reason he shouldn't take over Sky...!
How many big business out there know exactly what their employees are doing at all times, and how all the results happen? Probably very few: Hell, there's only 6 of us at my firm but I couldn't tell you what everyone is doing right this instant or exactly how they're going about their jobs, I just have to have a little bit of trust in them. Make that into hundreds of people and it's even more difficult to do. Yes, people at the top do have a responsibility to ensure that things are done correctly, but they can only do so much.
Whether you actually like/read The Sun and/or NOTW, what isn't really known is that they're incredibly highly respected amongst their peers as generally they are at the cutting edge of the English language. That gets a scoff from everyone I tell, as it used to from me when my A-Level lecturer told me the same thing, until we sat down and analysed just how the Sun used language compared with the broadsheets. It opened my eyes significantly, and reading different papers from that viewpoint to this day I can see that nothing really has changed. You can use all the big words you like, but that doesn't always make for the best journalism.
FWIW I actually couldn't have cared less about the celebrities getting their phones hacked and pretty much ignored the whole story, but this thing about deleting the Dowler messages makes me sick to my stomach. Utterly disgusting, but we must only appoint blame where it is clear IMHO.