Correct.

Visual/spatial functions of the right hemisphere are mostly perceptual. With sign language, signs are incorporated into a formal system (more specifically, a language) which is imbedded into the left hemisphere of the brain. People who have sign language as their primary language are subject to the same kind of language disorders as those who use spoken language; such as Broca's or Wernicke's aphasia, which are caused by damage to (parts of) the left half of the brain.
http://www.lifeprint.com/asl101/page...sticsofasl.htm

"Signers" affected with aphasia do not lose their ability to make and interpret non-linguistical gestures. Conversely, loss of these functions (seated in the right hemisphere) do not affect a signer's ability to interpret or make linguistical signs. For example, a signer might lose the ability to interpret simple gestures like a shrug or waiving a fist, while retaining the ability to interpret complex linguistical gestures.
In other words, the ability to make or interpret linguistical gestures is largely, if not completely independent from other visual/spatial functions of the brain.

Most of the info is taken from Oliver Sacks' Seeing voices.
See also:
http://www.ncbi.nlm.nih.gov/pubmed/6668233

Your turn, Telly