Thanks for the book review of Peter S. Beagle's Innkeeper's Song. I immediately rushed out and bought myself a copy and read it over the holidays. It is something of an occassion when Mr. Beagle (who lives near Drury in Davis) breaks his silence - thanks for sending out the alert!
You ask if the unnamed magician in Innkeeper's Song is the same Schmendrick of The Last Unicorn. If by this you mean that the Song is a sequel to the Unicorn, or even that it is a subsequent tale from the same fictional universe, I think the answer is no. However my own (limited) experience as a writer causes me to believe that the two magicians come from the same part of Beagle's heart. That is, Schmendrick is the wizard of a young man's heart and the innkeeper's magician is the wizard of that same man's heart a few decades later. In that sense, they are both the same wizard.
I have a sneaking suspicion, by the way, the Peter's eyes are green.