Here's another spoiler, but it's in French. I don't know what it says exactly but it's about the filming dates at Pierrefonds.

Dates de tournage à Pierrefonds ( saison 5 )
by "Colin Morgan" on Tuesday, February 21, 2012 at 7:18am ·

Voici les dates du tournage de la saison 5 de Merlin en France, provenance de l'Office de Tourisme de Pierrefonds :

Premère sessions du 14/06/2012 au 27/06/2012

Deuxième sessions du 06/09/2012 au 14/09/2012

sous réserve de modifications.

Il semblerait que le tournage ne compte que deux sessions cette année, la session mars-avril ne figure pas en tête de liste ...

TOUTEFOIS... rien est encore OFFICIEL et tout est approximatif donc patience ...

source - Mist of Camelot - link

Murphy Interview: New female characters, Gwen and Morgana go on a Journey, two new characters and others:

link

Part 2 of the Murphy Interview for S05:

link

Well, I really don't hope they will make an animated series or a film! Merlin should stay as a TV-show! ;B

And sad we probably won't see any more of Lancelot :( Buhuuu! :'C But hey! We've got an older Mordred! Weeee! ^w^

I'm very excited for the upcoming season! I think it's going to be brill! ^w^ <3

I found this on Tumblr:

link

9 of the episodes for S05 will be directed by Justin Molotnikov, Ashley Way, and Alice Troughton. And, if you read the other posts, it seems the cast and crew read fanfic from Merlinians...

Cultfix says the Airdate for MERLIN is slated for September 29, 2012 in the UK. One week after the end of DR. WHO:

link

John Bradley plays Tyr Seward and James Fox plays King Rodor in MERLIN S05:

link

So, John Bradley West and James Fox will be on MERLIN S05. Playing Tyr Seward and King Rodor respectively:

link

Some news from SDCC 2012

link