Sorry, I'm over posting here but I just had to put this up because it was something that didn't even cross my mind. Here's the quote which is from datacenterknowledge.com but which I got through Dare Obasanjo who pointed to Slashdot who in turn pointed to this...
The business implications of Microsoft's offer are huge. From a data center perspective, the deal would consolidate two of the largest Internet infrastructures. In a letter to Yahoo's board, Microsoft said that "eliminating redundant infrastructure and duplicative operating costs will improve the financial performance of the combined entity." A consolidation of the two companies' networks could shift a massive amount of infrastructure from open source technologies to Microsoft platforms.
I have tons of criticism for the blogosphere but this is where it really shines in that I didn't even think of this. Microsoft is certainly going to make the eventual conversion to Windows Technology a condition of this agreement and there are undoubtedly some in Yahoo who are going to object to it. But the people objecting are probably going to be pretty low level folks who aren't going to have a lot of say in the matter. Assuming Microsoft already has a plan that accounts for the transition I don't think this is going to be a sticking point. I will be curious to see how significant a change Microsoft is going to want though (is Php and MySQL on a Windows box OK or does everything have to be rewritten for .Net and SQL Server?)
With all that said lets keep this in perspective, mergers do not happen quickly and the merging of technology doesn't happen until after the merger is complete. It may very well be years before we see the repercussions of this deal on Yahoo's current setup.