The version number of TeX is converging to π and is now at 3.141592
On a side note: I can't but wonder at all things Knuth:
Remember his words about email:
I have been a happy man ever since January 1, 1990, when I no longer had an email address. I'd used email since about 1975, and it seems to me that 15 years of email is plenty for one lifetime.
He quitted in the best moment, right before spam came in. A true visionarie!
And this chapter of xkcd was terribly funny too... not that it is directly a Knuth-thing but it is related and came to my mind :-)