Most recent webservice is available here: /Retailer/V26/MediaService.asmx
Links to documentation:
Pubhub Integration Guide v1.4 April 2013.pdf
PubHub Slutbrugervejledning.pdf (Dansk/Danish)
PubHub Slutbrugervejledning.doc (Dansk/Danish)
PubHub Slutbrugervejledning.htm (Dansk/Danish)

The following operations are supported. For a formal definition, please review the Service Description.

• CancelOrder
  Cancel an order.
  An order can only be cancelled as long as the customer has not tried to download the book.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  orderNumber*: The retailer order number identifying the order to be cancelled
  
• CreateSupportCase
  Creates a support case.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  message*: The support message
  creatorEmailAddress: The creator's email address
  orderNumber*: The order number to which the support case belongs
  
• GetBook
  Get book with the id given by "bookId".
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  bookId*: The bookId to return
• ListAllBookIds
  Lists all available book IDs.
  Use the list of book ids that this method returns as argument to the method ListBooks(Guid licenseKey, Guid[] bookIds)
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  
• ListAllBookSubjects
  Lists all book subjects.
  BIC (Version 2, revision 01) is supported.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  language*: Enum defining the language of the returned subjects (DAN=Danish / ENG=English)
  
• ListAllBooks
  Lists all available books.
  Caution: This methods returns alot of data. To avoid problems increase the timeout in your web service client.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer.
  
• ListBooks
  Lists books with the ids given by "bookIds".
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  bookIds*: An array of bookIds
• ListModifiedBookIds
  Lists book ids added, updated and deleted after "afterUTC".
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  afterUTC*: UTC date and time after which the books should have been added/updated/deleted
  
• ListModifiedBooks
  Lists books that have been added, updated and deleted after "afterUTC".
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  afterUTC*: UTC date and time after which the books should have been added/updated/deleted
  
• ListOrders
  Lists all orders between two dates
  All parameters is required
• OrderBook
  Orders a book.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  orderNumber*: A unique number identifying the order
  bookId*: Id of the book to order
  enduserEmailAddress: Optionally the end user's email address to send an email containing the download url directly to the end user. Use NULL to not send an e-mail.
  
• OrderBookByIsbn
  Orders a book by Isbn13.
  CAUTION: Publishers are able to change Isbn13 numbers. Hence it's recommended to use OrderBook (with parameter Guid bookId).
  If this method is used it's important to stay 100% in sync with metadata (using ListModifiedBookIds/ListModifiedBooks) ensuring possible updates of isbn13 numbers.
  Parameters (*=required):
  licenseKey*: Guid identifying the retailer
  orderNumber*: A unique number identifying the order
  isbn13*: Isbn13 number of the book to order
  enduserEmailAddress: Optionally the end user's email address to send an email containing the download url directly to the end user. Use NULL to not send an e-mail.