I like the way that My Starbucks Idea login button has been incorporated into the instructional text that goes with it.
Placing the button within the text makes it fit more naturally with the wording and I like the economical use of space. Maybe I also just like the fact that it feels a bit different.
That being said, if you don’t already have an account, there is no sign up button so you have to click ‘Sign In’ first in order to be presented with the option to create one. That seems a little clunky.
I don’t recall too many other examples of button placement like this — in fact, none come to mind right now. I’d be interested to hear about any other examples.