Ron Silliman points to this post with the statement Why memorizing poetry is inherently right wing. The question of memorization is, of course, sometimes an important one for musical performance as well and sometimes we musicians also make a similar distinction between rote and "by heart" memorization. Generally speaking, the pro-memorization camp is our conservative party and it is typical for competitions and recitals on the establishment circuit to insist that musicians play without sheet music visible on stage. (This insistence comes with that same weird macho-but-prissy swagger that only conservative pseudo-intellectuals carry.) While there are cases in which getting rid of the paper is unavoidable — in opera, for example, or with some percussion instruments for which visual contact with a music stand cannot be maintained —, I side decidedly with the opposition party here. This is because when playing notated music one can too frequently discover that notation is a gift that keeps giving; reading music is seldom a task which is completed with rehearsal and a live performance is often a valuable additional opportunity for discovery. This possibility was brought home to me first by playing baroque music, realizing continuo and ornamentation in real time.
Addendum, 14/4/2010: I think that I wasn't clear enough here. My problem is not with memorization but with the insistence than musicians play without notation and the deprecation of musicians who chose to use notation. Although my own memory is probably average, when I rehearse something well, it is almost inevitably committed to memory, but I still want to have the notation available. And not for insurance but out of optimism, that there is still more music to be found in the act of reading.