Here is an article that PJ is also covering at Groklaw:

Microsoft Corp has admitted execution flaws with its promise not to sue open source software developers and invited the wider community to tell the software firm how it can get it right.

Apparently, Miguel De Icaza and Nat Friedman had expressed some displeasure or reservations about the covenant as it stood. MS isn't completely backing off though:

Our design goal is to get language in place that allows individual developers to keep developing. We are not interested in providing carte blanche clearance on patents to any commercial activity - that is a separate discussion to be had on a per-instance basis

Still unacceptable, but MS is apparently willing to listen.