The time was nigh. My Touch software was at v 3.1.2 and many of my apps would no longer update, yet the computer to which the iPod was beholden was about four computers back, so I would lose every app I've ever downloaded - something to the tune of 4GB of them.
Nonetheless, waiting until every app was at its lifecycle end for the operating system seemed silly. Besides, I didn't want to lose any new apps I downloaded and many new ones were 4.0+ only.
I bit the bullet and updated.