As soon as you mentioned it, I realised I had been imagining a Patrick Stewart like person for Barristan Selmy as well.

I found another thread talking about casting... http://www.aintitcool.com/talkback_display/40001 Some good choices there.  

I had been wondering who would make a good Tyrion, and they named the perfect choice.  Peter Dinklage: http://www.peterdinklageonline.com/sitebuildercontent/sitebuilderpictures/dinklagethreshold1.jpg

They also name James Purefoy for Jaime.  http://www.hbo.com/rome/img/cast/actor/actor_jamespurefoy.jpg

Daniel Day Lewis for Eddard? http://img372.imageshack.us/img372/1406/thxdanielliquidor6.png

Geoffrey Rush for Littlefinger?  http://www.applause-tickets.com/blog/uploaded_images/pro_c_GeoffreyRush-758793.jpg  I always pictured him younger though.

Victoria Pratt as Cersei?  http://images.askmen.com/galleries/model/victoria-pratt/pictures/victoria-pratt-picture-1.jpg

What about Henry Cavill (from Tudors) as Jon Snow?  http://hotcelebs.today.com/files/2009/02/henrycavillcb.jpg

I don't know that I agree with the littlefinger choice, only because he is supposed to be a fairly young man.  The ages of the characters in the book will obviously have to be adjusted so that certain characters who get married in the story (eg Sansa Stark) are at a more appropriate age for modern society.  Still, I think Geoffrey Rush looks about 10 years too old (having grown up with Catelyn Stark and her sister).

Similarly, I picture Jon Snow being 18-20 for the purposes of the show.  Henry Cavill could be a good choice, as long as they keep him looking young (as long as he's always clean shaven, it should be fine).

Other than those two points, I think those are perfect choices!

How about Tim Roth as Littlefinger?  http://www.daemonstv.com/wp-content/uploads/2009/02/tim_a4u6914rc-333x500.jpg

Good choice!

Looks like Diddly hit the nail on the head for Tyrion!

http://www.hollywoodreporter.c.....3652295a5a9e328518de

Sweet!  This movie/series is looking better and better!  I doubt we'll get any of our other picks though.

Catelyn Stark has apparently been Cast.  She will be played by Holly Marie Combs (from "Charmed".

http://us.imdb.com/media/rm2609682688/nm0001061

Better and better!!  Ice and Fire Video games are finally in the
works!

http://grrm.livejournal.com/90917.html

Well, more casting news for "Game of Thrones": Jennifer Ehle has been cast as Catelyn Stark.

http://grrm.livejournal.com/97759.html

Someone named their child after Catalyn Stark?  How retarded is that... The husband vetoed the name Arya...

More casting has been done, for seven of the roles: Dany, Jorah Mormont, Jaime, Arya, Sansa, Robb Stark and Theon Greyjoy.

http://www.hollywoodreporter.com/hr/content_display/news/e3iebbbd387ec9a77d4420b06999a24352b

and, as always:

http://grrm.livejournal.com/

Cersei is cast:

http://grrm.livejournal.com/106073.html

Good choice she's got a sassy look to her too.

When is this thing going to air?

I think shooting is scheduled to begin in October, but I'm not going to swear to that.  If they've announced a target for the air date, it's probably listed in one of the earlier links in this thread.