108,400 in 92 countries.
Add roughly 20,000 more employees for our "subsidiary" companies.
North American headquarters is in Pittsburgh, and there's about 8,000 of us. The rest (9,000 or so) are spread out in 65 sites around the US and Canada.
Edit: All numbers are "FTEs." We employ about 40/60 contractors to employees, so you can basically double the number if you want to count contractors (who sometimes have more tenure than employees).