I came across this interesting article on how Jim Allchin has championed developing Windows Vista in a more agile way.  He mentioned several times in his PDC keynote that Microsoft had changed the way they were developing software, but didn't provide many details.  Here's an example:

We feel very confident about broad availability [of Windows Vista] by the end of 2006. Now, why do we feel that confidence? We feel the confidence because we re-did the way we were building Windows. During the last two years, we completely re-engineered engineering

Microsoft have always prided itself that it understood how to ship software, so it's interesting to see them reflecting on the problems with their current approaches and how they can be improved.

Here are some interesting points:

• They have reduced the amount of time spent integrating components together by sorting out the dependency between components.  Knowing these dependencies, and working on minimising them (sounds like architecture to me), is enabling Microsoft to leave up components that don't pass 'quality gates'
• They are reducing the idea that 'pulling an all nighter' and being a heroic developer is something to admire:

In 2001 Microsoft made a documentary film celebrating the creation of Windows XP, which remains the latest full update of Windows. When Mr. Allchin previewed the film, it confirmed some of his misgivings about the Windows culture. He saw the eleventh-hour heroics needed to finish the product and get it to customers. Mr. Allchin ordered the film to be burned.

• Bill Gates being was worried about upsetting the status-quo, 'taxing' the developers with process and was concerned about backlash from the developer teams.
• They are finding a lot of value in automated testing tools.  One thought that has been bouncing around my head since the PDC is the comment that Jeffrey Richter made about the problem where a method was added to a class as an instance method, when all other methods were static and the constructor was private, which meant that the instance method could never been used.  As Jeffrey Richter said, it's clear that the developer had not written a single test to check his (I know it was as a he - the guy owns up to the mistake in Brad Abrams' excellent new book 'Framework Design Guidelines') work!  Clearly Microsoft have a way to go in getting test infected.
• Reducing the build time of the product has meant they are getting greater feedback more quickly.

Recently I've been in the position of working with an ex-IBM Architect and an ex-Microsoft Dev Lead. It's been interesting to see the differences in backgrounds and perspectives, which broadly fall into the differences between Architecture and low-level system Development.  An example was a discussion about finding the distance between a point and a rectangle.  The Developer had come up with a patented approach to solving the problem in an extremely efficient way, but the Architect wanted to know why the problem only considered rectangles, and whether it couldn't have been abstracted further to consider many different types of shapes.

The discussions have helped me see the value of both approaches, but overall, the need to architect a solution well, since it is easier to find faster algorithms, but if things haven't been architected well it's a great burden to refactor the structure of the code.