The USGS has just released the 2011 National Land Cover Database (NLCD 2011) for the State of Alaska. This product has a 30 meter spatial resolution with 20 land cover classes. When used with the NLCD 2001 dataset it provides an objective decadal look at land cover change in Alaska. The greatest change during this 10-year period was conversion of forests to shrub and grasslands due to increased forest fires.
The NLCD 2011 product was released for the lower 48 states last year and Hawaii and Puerto Rico will be released later this year.
The data can be downloaded for free from the Multi-Resolution Land Characteristics Consortium (MRLC) at: http://www.mrlc.gov/
You can read the USGS announcement at: