In addition to Shakespeare's, quite a few of Sidney's sonnets, too. (The first one in Astrophil and Stella, or the one that ends "I am not I. Pity the tale of me." !!!)
Yeats." In Defense of Poetry," by Edgar Bowers, which I'd post but don't have right now (work). Wyatt's My Lute, Awake!
http://www.luminarium.org/renlit/myluteawake.htm, which isn't really about poetry so much as dependent on the conceit of poetry, but I mention it anyway because I love it. Several excellent poems from Stevens's Harmonium.
Awesome translation, Bob. I suppose "El rimordimiento" could also be considered a poem about poetry, or about the choice to be a writer, anyway? Can you post your version of that, Bob, assuming you have one?
Speaking of which, Nabokov had a funny poem about translating Eugene Onegin, in which he described his version as bird droppings on the statue of the original.