The following U.S. volcanoes are known to be above normal background (elevated unrest or eruptions) or have shown activity that warranted an Information Release (for example, an earthquake swarm).
Times are local to the volcano and in military format.
Volcano Alert Levels & Aviation Color Codes defined at

• Iliamna Alert Level=ADVISORY. Aviation Color Code=YELLOW. As of Mar 13, 2012, 13:42 AKDT
  Seismic activity remains above background.
  (Change to current status occurred on Mar 9, 2012 13:07 AKDT from Alert Level NORMAL and Aviation Color Code GREEN )
  For more information see http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=7081
• Cleveland Alert Level=WATCH. Aviation Color Code=ORANGE. As of Mar 13, 2012, 13:42 AKDT
  No additional activity detected.
  (Change to current status occurred on Jan 31, 2012 15:21 AKDT from Alert Level ADVISORY and Aviation Color Code YELLOW )
  For more information see http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=7082
• Kilauea Alert Level=WATCH. Aviation Color Code=ORANGE. As of Mar 13, 2012, 08:01 HST
  DI inflation; summit lava lake rising; active flows to the SE of Pu`u `O`o on coastal plain; gas emissions elevated.
  (Change to current status occurred on Mar 9, 2011 19:45 HST from Alert Level WARNING and Aviation Color Code RED )
  For more information see http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=7080

Pagan Alert Level=ADVISORY. Aviation Color Code=YELLOW. As of Mar 9, 2012, 09:13 ChST
YELLOW/ADVISORY. Persistent steam/gas plume.
(Change to current status occurred on Oct 6, 2011 14:21 ChST from Alert Level UNASSIGNED and Aviation Color Code UNASSIGNED )
For more information see http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=7065

http://volcanoes.usgs.gov/activity/alertsystem.

http://www.volcano.si.edu/reports/usgs/

world wide

http://volcanoes.usgs.gov/activity/elevated.php