The short answer is, more than last week!
BirdLife International has been working with Lynx Edicions on the production of the Handbook of the Birds of the World/BirdLife Illustrated Checklist of the Birds of the World, which will become the taxonomic standard that underpins BirdLife’s work. Taxonomic changes for non-passerines (ie not the perching birds) will appear in Volume 1 of the Checklist (to be published in August 2014). Changes for passerines (the perchers) will appear in Volume 2 of the Checklist (probably in 2016).
In total, the taxonomic work behind the Checklist has led to the recognition of 361 new species of non-passerines, all of which have been assessed against the Red List criteria and documented for the 2014 Red List update. Additionally, the global status of a number of other species (both passerines and non-passerines) has been reviewed and revised, according to the latest available information.
To find out more, visit the BirdLife webpage. You can also join in taxonomic discussions on BirdLife's globally threatened bird forums, and find case studies in the Data Zone under State of the World's Birds.
In case you think I had forgotten….overall, BirdLife now recognises a total of 10,426 species worldwide, of which 13% are threatened with extinction.