Google says "Results 1 - 10 of about 1,990,000 for artifical. (0.14 seconds)"
While Google says "Results 1 - 10 of about 213,000,000 for artificial [definition]. (0.08 seconds)"
If there are more than 1 million results for a misspelling, then it's safe to say that it's common enough to warrant its own entry that it is a misspelling of a word.
- There is also an appalling number on Google Book Search (though many are OCR errors). SemperBlotto 16:24, 14 August 2006 (UTC)