Playing with a sample session for possible inclusion in the tutorial, I've found that '|' is not nearly as clear in its intention as '+'.
It's way too early to say that. I actually like the fact that | and & are a new vocabulary (for containers at least) so they provide an additional hint that we're dealing with a different kind of container. For sequences, a+b != b+a (unless a==b). For sets, a|b == b|a. That's a useful distinction. + is already used for two distinct purposes: for numbers (where it is symmetric) and for sequences (where it is not). But numbers and sequences are unlikely to be confused because they are used so differently. Sets and lists are both containers, and I think it's useful that their vocabularies don't overlap much. --Guido van Rossum (home page: http://www.python.org/~guido/)