Yes, but they're often used for "mere" interpolation, especially in languages where, rightly or wrongly, string concatenation is believed to be inefficient. I personally do this nine times out of ten, if only out of habit.

For my part, I've never personally liked the use of "+", in particular, to denote concatenation, for the (admittedly silly) reason that string concatenation is not commutative. If nothing else, it's a bit of a slippery slope to even more dubious operator overloads, though not nearly so much as C++'s bloody I/O "operators"!