When I first heard about collaboration for development teams it seemed to have very soft benefits, and was hard to quantify. But I've been thinking about it in the context of lean, and realized collaboration is critical to improving a development process - and collaborative tools may well be the key to unlocking that improvement.
When you think about software development in terms of a lean process, then an average team will have a process efficiency of about 20% ( i.e. only 20% of the time taken to deliver a feature is spent on useful work or another way of thinking about this - 80% of the time is wasted in waiting and hand offs).
So when you start applying tooling to this environment you have to ask yourself what is going to give you the biggest improvement - either automating tasks for the individual practitioner, or trying to tackle the waste and hand offs ?
Just looking at the numbers, it's obvious you're going to get less return by focusing on tools that just help individual productivity e.g. If you implemented a set of non-integrated tools which boosted individual productivity by 20%, then the piece of work which was taking 100 days is now taking 96 (you still have 80 days waste, and you've reduced the 20 days to 16). Contrast this with tooling and process changes which focused on the hand offs and waste, and which reduced that by 20%, and that 100 day task is now taking 84 days instead ( you're still doing 20 days work, but you've reduced the waste to 64 days).
The diagram below gives a view of what happens when you dramatically reduce the non-productive time – naturally the time to market/ development time is dramatically reduced too.
Now in reality you obviously want to automate more (to reduce the time taken to do the work), and also collaborate more to reduce the waste and hand offs. But these numbers make it apparent why collaboration is so critical - to make a significant impact on your process efficiency and delivery time, you have to really tackle the hand offs and other sources of waste - and collaborative, integrated tools are what help you and your team to do that.
If you're interested in how IBM Rational's tools can help - then you might be interested in this article I wrote a couple of years ago http://ibm.co/steve_lean.