Thanks to the Scottish Genes Blog (http://scottishancestry.blogspot.com/) for an update. 

The National Library of Scotland has a new dedicated Post Office Directories page on its website at www.nls.uk/family-history/directories/post-office. There are 287 directories currently available from 1774-1911. You currently can only browse or download the Directories but a full search function is expected in March 2011.

From the same blog: The 18,000 Scottish maps from the library's online collection have now been made available at the ScotlandsPlaces website at www.scotlandsplaces.gov.uk. ScotlandsPlaces is a website that lets users search across different national databases using geographic location. The user is able to enter a place name or a coordinate to search across these collections or they can use the maps to both refine and define their search.