Nope, that's an older version than http://math.mit.edu/~dspivak/CT4S.pdf http://math.mit.edu/~dspivak/CT4S.pdf . The date you see under the title is the date wh

Nope, that's an older version than http://math.mit.edu/~dspivak/CT4S.pdf http://math.mit.edu/~dspivak/CT4S.pdf . The date you see under the title is the date when the file was last compiled (which is done automatically by arXiv every once in a while), because arXiv is still too stupid to redefine \today when compiling files. The date in grey on the left margin of page 1 is the right one. The proper new version has been published by MIT press in 2014 and can be downloaded from the usual places where books can be downloaded.