According to sales statistics compiled by the Association of American Publishers (AAP), trade eBook wholesale sales from reporting publishers were $46.6M for November 2010, a 129.8% increase over November 2009 ($20.3M), and an increase of 14.5% over the the prior month of October 2010 ($40.7M). Calendar Year to Date sales (11 months) increased 165.3% from $147.9M in 2009 to $392.4M in 2010.
Note that the usual caveats to this data apply -- specifically around the number of publishers contributing data. These numbers are typically seen as a conservative estimate.
Statistics, historical data and information about eBook sales can be viewed at: http://www.idpf.org/doc_library/industrystats.htm (NOTE: the IDPF website is being revamped and this page will not be updated until the new site is launched later this quarter).