Clavier is an excellent magazine, but is more oriented toward piano teachers than students. It's still worth subscribing to though, as there are insights there for everyone. The fact that it's not published every month gives you something to look forward to.
Piano Quarterly was probably the best publication ever, but was sold after the death of one of its owners, and was redubbed Piano & Keyboard. The latter, although very good, (in fact the former editor of Piano Quarterly rejoined the publishing staff to improve it), was never quite the same quality as the predecessor Piano Quarterly. Sadly, to the best of my knowledge, Piano & Keyboard stopped publishing in 2001. The holding company then pushed a magazine called Keyboard, which featured electronic instruments and equipment only. Those of us who were interested in accoustic piano and serious music dropped it instantly at the change.
There is a fine magazine called Piano, International Piano Quarterly. This is published in the UK, unlike the American offerings mentioned above. It covers all aspects of piano really well--artists, concerts, competitions, pedagogy, composers, discography, repertoire, reviews, you name it. It's a very high quality journal.
Topic: Piano magazine?