Simple - not easy
Few companies of any size do it effectively; some do it very well, some do not. Not just projects involving IT. Whether you do it in your company, is your choice. And, as with The Deal, you can either choose to run your company like that, or you can do choose to do something about it.
Here's what to do:
Nothing - OK - then keep doing what you are doing / not doing now - just stop pretending you want to do something about it
The Small step - Have a list of all projects across your organisation and put them into clusters, One, Two and Three - or Red, Amber or Green, or whatever. Upside it can happen fast, downside is everything gets put in category one.
The Big One - Have a list of all projects across your organisation and list them in importance. Only the Board can do this and they won't do it unless they are encouraged / provoked. Best way to do this is to take a list to them and say that is the one you will be using unless they do it.
Benefits and Watch out fors...
Benefits - You are running a business, this is the way to run a business; everyone knows what is important and what is not; Saved time; Resource allocation; Plus many others
Watch out for - Locally developed systems that become mission critical (will happen, make sure someone in IT knows about them), people flying in under the radar with tactical projects and the big one that governs the success of all of this - be prepared, by professional and be business - it's not just OK to say "No" at times, it is absolutely imperative.