I'm not a huge fan of SOAP. It's pretty telling that somehow the letters don't stand for anything anymore -- it's just SOAP. "Okay, right ... so, it's not 'simple,' anymore, but we don't know what the hell it is now." That's worse than those silly recursive acronyms, and easily as irritating as words like "Ajax" that look like acronyms, but aren't -- "it's just a shorthand." Riiiight.
My experience with SOAP is that it's overly convoluted, and the tools are finicky to set up and use. When something goes wrong, it's hard to figure out the cause without firing up Ethereal. I'm actually happy to see Google moving away from SOAP -- I think it's a win for simplicity over needless complexity.
However, having said that, this change at Google does impact me a little because there is code in my book that uses the Google SOAP API.
The Ajax search app in Chapter 7 hooks into the Google SOAP API (among others) using a PHP backend proxy page (there's code for both the compiled-in extension and the PEAR library), and now obviously anyone wanting to try that code out will be SOL, because Google is no longer issuing keys to use that API.
It looks like they continue to support existing users for awhile at least, which is nice. So if any of y'all are reading Chapter 7, and for whatever reason really, really want to play around with Google's SOAP API, send me an e-mail, and I can dig up the key I got when I was working on that part of the book.