Yep, I think we covered this a while back.
Communication is the 3 V's, Verbal, Visual, Vocal: Words account for 7%, tone of voice accounts for 38%, and body language accounts for 55%.
Since in written communication we don't get Tone of Voice or any Body Language cues, we're only getting 7% of the message, the use of smilies helps improve that by at least giving us a (crude) visual cue.
jus' sayin'
BTW Nice to see an old/new face around here.