From Marylaine Block's February 4 Neat New Ex Libris newsletter.
Libraries Matter is a "promotional campaign, using blue wristbands with this motto. Order them here, and post your specific library cause you'd like people to donate to."
Done by the Alliance Library System of Illinois but open to all libraries. Personal orders aren't possible, but you can order wholesale for your library. My guess is they got the idea from the yellow bracelet promoted by Lance Armstrong, with the words "Live Strong" on it worn by cancer research supporters.