There's this heated discussion going on at the ALT.NET forum about Unity, a lightweight IOC container coming from P&P (make sure that you pick up this post at ALT.NET Pursefight). I blogged about this in the past here and here, so I'm not going to repeat my standpoint on this matter.
What I do want to mention is the fact that, to me, Microsoft seems to be solving yesterday's problems, not always in a successful way.
While the open-source community is working on solutions for today's problems (e.g. AOP, BDD, ...), Microsoft is following the more established OSS projects (NUnit/MbUnit, NHibernate, Castle Windsor/Monorail, etc. ...).
As far as I'm concerned, I like some more of this:
This shows that there are some people at Microsoft with some common sense.