How can I get Selenium Web Driver to wait for an element to be accessible, not just present?

Question

I am writing tests for a web application. Some commands pull up dialog boxes that have controls that are visible, but not available for a few moments. (They are greyed out,

Answer 1

    print time.time()
    try:
        print "about to look for element"
        def find(driver):
            e = driver.find_element_by_id("createFolderCreateBtn")
            if (e.get_attribute("disabled")=='true'):
                return False
            return e
        element = WebDriverWait(driver, 10).until(find)
        print "still looking?"
    finally: print 'yowp'
    print "ok, left the loop"
    print time.time()

Here is what we ended up with. (Thanks to lukeis and RossPatterson.) Note that we had to find all the items by id and then filter by "disabled". I would have preferred a single search pattern, but what can you do?