Veteran education correspondent John Merrow takes up the subject of community colleges in a new documentary, “Discounted Dreams: High Hopes and Harsh Realities at America’s Community Colleges,” which will begin airing in May on PBS (check local listings). For a taste of things to come, check out the first in a series of podcasts, this one, a conversation with three community college presidents about some of their hot-button issues. The podcast and the "Discounted Dreams" website will go live on March 19 at  www.DiscountedDreams.org.