Writer's Fallout Shelter

We've discussed POV before. We will do so again.

Over at Miss Snark's [http://misssnark.blogspot.com/2006/10/multiple-pov.html], a writer has asked if it is wrong to have the character's first person thoughts when writing in third person limited.

Personally, I don't think it is. If the writer is in the character's head and telling the story from the character's viewpoint, then the character's thoughts are known to the writer and can be shared.

I am interested in hearing your thoughts. Does staying in POV mean another type of pronoun can never be used? Should the writer not share the POV characters internal thoughts in third person?