Also 1 site update, or version number, could really be N releases until fruition -- which don't sound like traditional releases to me.
What he's saying is more about convention than writing code. For instance, instead of adding a column "abc" and doing:
foo.abc = 123;
they would do something like:
if (foo.abc) { foo.abc = 123; }
make sure all tests pass, and then migrate the db.
If you're asking about tools to migrate code, all popular languages have one. (I.e. django comes with one that's already really good).
Also 1 site update, or version number, could really be N releases until fruition -- which don't sound like traditional releases to me.