Having recently completed my MCTS and MCITP certifications for Business Intelligence on MS SQL Server 2005, I find this move interesting on Microsoft's part. I have found PHP to be an excellent tool for manipulating CSV files as part of an ETL (SSIS) process. On the web side of things, I have found PHP to be a very capable tool. It integrates tightly, at least with Apache, and fits nicely into a MVC model. I have been able to run the same PHP app under Apache on both Linux and Windows without any changes.
As for the package Microsoft is offering here, there is nothing PHP specific other than some samples. Sounds like a good deal in terms of functionality though. A very good intro to the world of Microsoft.
It would be my observation that IIS tends to get the nod for intranet purposes and Apache gets the call for internet applications. Herein lies the litmus test for Microsoft: Is the fastcgi interface under IIS truly good enough? Or will Microsoft feel the need to develop a more tightly coupled PHP interface for IIS? Time will tell.