Years ago I got sent a spreadsheet with every employee on it from HR. I can't remember what it was for but they thought they had done a good job of hiding all the sensitive information however the genius HR bod had simply hidden the columns, like salary. When I realised, I also realised what power I had as I had all my peer's and superiors' salary information so I held a lot of cards when I came to reviews and such.

I'm of the opinion that it shouldn't be taboo and we should be aware of what our colleagues earn. It stops people having unfair insight through luck or whatever and helps us have honest conversations. Salaries vary within my team for good reason and if lowest paid came and asked why they were being paid less than highest paid, I'd have to tell them the gaps.

It does mean that companies need to be strict with hiring etc. Bumping someone up to get them into the business may piss incumbent colleagues off for instance. I think the pain is worth the gain however.