The code in the this module is intentionally obfuscated code, as a joke,* so the string as-is doesn't directly appear anywhere.
However, if you look at the source (e.g. print inspect.getsource(this), or looking in the source repo), you'll see that the last line is:
print "".join([d.get(c, c) for c in s])
… which means the answer is:
text = "".join([this.d.get(c, c) for c in this.s])
Of course that's relying on undocumented, implementation-specific details, but then the this module itself is undocumented, implementation-specific details, as can be seen by looking at the library reference.
However, if you want something that works with any Python implementation that has a this module that prints things out even if it's implemented differently (which would be not a single Python implementation that exists, as far as I know…), you could always do this:
old_stdout = sys.stdout
sys.stdout = StringIO.StringIO()
try:
import this
text = sys.stdout.getvalue()
finally:
sys.stdout = old_stdout
However, keep in mind that import only runs the code on first import, so if you do this twice in the same session, you're going to end up with '' the second time.
Another fun option is to download PEP 20 and parse it with your favorite HTML parser to extract the text. But I'll leave that as an exercise for the reader.
* In case you're wondering, the joke is that obfuscating source code, reimplementing rot13 from scratch, even though it's built into the stdlib, doing it with a nested loop, looping over 65 to 97 instead of the characters, looping over range(26) for a reason that you have to read the code multiple times to understand… all of this violates the Zen as badly as possible. See Barry Warsaw's post for a bit more background on their state of mind at the time they implemented it.