Editorial Advisory Board
Eric Allman
Charles Beeler
Steve Bourne
David J. Brown
Bryan Cantrill
Terry Coatta
Mark Compton
Ben Fried
Pat Hanrahan
Marshall Kirk McKusick
George Neville-Neil

Sales Inquiries Jonathan Just 212-626-0654 jonathan.just@acm.org

Contact Points Queue editorial queue-ed@acm.org

Queue advertising

queue-ads@acm.org

Copyright permissions

permissions@acm.org

Queue subscriptions

orders@acm.org

Change of address

acmcoa@acm.org

ACM Queue (ISSN 1542-7730) is published ten times per year by the ACM, 2 Penn Plaza, Suite 701, New York, NY 10121-0701. POSTMASTER: Please send address changes to ACM Queue, 2 Penn Plaza, Suite 701, New York, NY 10121-0701 USA Printed in the U.S.A.

The opinions expressed by ACM Queue authors are their own, and are not necessarily those of ACM or ACM Queue. Subscription information available online at www.acmqueue.com.

Executive Director and CEO: John White Director, ACM U.S. Public Policy Office: Cameron Wilson

Deputy Executive Director and COO: Patricia Ryan Director, Office of Information Systems: Wayne Graves Director, Financial Operations Planning: Russell Harris Director, Office of Membership: Lillian Israel

Director, Office of Publications: Mark Mandelbaum Deputy Director, Electronic Publishing: Bernard Rous Deputy Director, Magazine Development: Diane Crawford Publisher, ACM Books and Journals: Jono Hardjowirogo

Director, Office of SIG Services: Donna Cappo

Executive Committee President: Stuart Feldman Vice-President: Wendy Hall Secretary/Treasurer: Alain Chesnais Past President: Dave Patterson Chair, SIG Board: Joseph Konstan

For information from Headquarters: (212) 869-7440

ACM U.S. Public Policy Office: Cameron Wilson, Director 1100 17th Street, NW, Suite 507, Washington, DC 20036 USA +1-202-659-9711–office, +1-202-667-1066–fax, wilson_c@acm.org

ACM Copyright Notice: Copyright © 2008 by Association for Computing Machinery, Inc. (ACM). Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and full citation on the first page. Copyright for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, or to redistribute to lists, requires prior specific permission and/or fee. Request permission to republish from: Publications Dept. ACM, Inc. Fax + 1 (212) 869-0481 or e-mail < permissions@acm.org>

For other copying of articles that carry a code at the bottom of the first or last page or screen display, copying is permitted provided that the per-copy fee indicated in the code is paid through the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, 508-750-8500, 508-750-4470 (fax).