The 2008.PRES.OBAMA Intrade contract now trades at 83.6, whereas the 2008.PRES.McCAIN Intrade contract is currently trading at 16.1 (compared with 77.5 and 23.0 respectively as reported on October 12, which was the the last time I posted an update on the Prediction Markets).
The state-by-state contracts imply that Mr. Obama holds a 364-174 “lead” over Mr. McCain (based upon my cutoff price point of 55 for allocating Electoral College votes). Since there are no longer any state contracts that are trading in the 45-55 range, this means that there currently are no “swing” states left (according to this pricing criterion, anyway). Missouri was previously a “swing” state, but the MISSOURI.DEM contract has rallied substantially and is currently trading at 66.9.
FiveThirtyEight.com currently gives Mr. Obama a 349.2 to 188.8 advantage over Mr. McCain.
Addendum: October 18, 2008 Electoral College Vote allocation
Barack Obama (364): California (55), Colorado (9), Connecticut (7), Delaware (3), District of Columbia (3), Florida (27), Hawaii (4), Illinois (21), Iowa (7), Maine (4), Maryland (10), Massachusetts (12), Michigan (17), Minnesota (10), Missouri (11), Nevada (5), New Hampshire (4), New Jersey (15), New Mexico (5), New York (31), North Carolina (15), Ohio (20), Oregon (7), Pennsylvania (21), Rhode Island (4), Vermont (3), Virginia (13), Washington (11), and Wisconsin (10)
John McCain (174): Alabama (9), Alaska (3), Arizona (10), Arkansas (6), Georgia (15), Idaho (4), Indiana (11), Kansas (6), Kentucky (8), Louisiana (9), Mississippi (6), Montana (3), Nebraska (5), North Dakota (3), Oklahoma (7), South Carolina (8), South Dakota (3), Tennessee (11), Texas (34), Utah (5), West Virginia (5), and Wyoming (3)