Those doubters who said McCain would never pick Romney and Romney would never accept are obviously too young to remember the Reagan-Bush Sr. relationship during the primaries. Pundits said it would never happen, but my mom said "Never say never". Lo, and behold, the two became running mates.
It looks like history is repeating itself. McCain and Romney are now jet-setting all over the west together with Romney now a prominent McCain campaign cheerleader. Look for the relationship to be confirmed shortly after the national convention.