Here are few remarks which might be relevant, although I understand almost nothing of the global Langlands program.

Lafforgue is currently working on problems relating to functoriality. There are a number of recent preprints and notes on [his webpage][1], see for example "Quelques remarques sur le principe de fonctorialité". If you don't read French, maybe the lectures of Lafforgue in Cambridge a few months ago would be useful. They are available in various video formats at the Newton Institute webpage. To find them, see [this list][2], and scroll down to May - there is a total of 5 talks by Lafforgue, the first one on May 5th.

My impression of Lafforgue's work is that he aims for a proof of functoriality in a fairly general setting, and (amazingly!) he hopes that the method would work also in the number field case and not only for function fields (although I might have misunderstood this). The method has at least some vague similarity with Tate's thesis, I think.

For more general background on functoriality and related things, see maybe Knapp's [survey on the Langlands program][3], the [Clay Summer School Proceedings][4] from 2003 (here is the [Google Books page][5]), and this [short note of Rapoport][6] on Lafforgue's earlier work.


  [1]: http://www.ihes.fr/~lafforgue/publications.html
  [2]: http://www.newton.ac.uk/programmes/ALT/seminars/index.html
  [3]: http://www.math.stonybrook.edu/~aknapp/pdf-files/245-302.pdf
  [4]: http://www.claymath.org/publications/Harmonic_Analysis/
  [5]: http://books.google.co.uk/books?id=TgPsXMXdJzUC&printsec=frontcover&source=gbs_navlinks_s#v=onepage&q=&f=false
  [6]: http://www.math.uni-bonn.de/people/may/rapoport/preprints/lafforgue.pdf