Here's an interview with the woman who was mauled and survived: http://abcnews.go.com/GMA/montana-bear-attack-victim-deb-freele-speaks/story?id=11277179
The above report uses bad info for the estimate of the bear population. According to the 2009 Interagency team report, close to 600 GRIZ live in the greater Yellowstone area (http://www.nrmsc.usgs.gov/files/norock/products/IGBST/2009report.pdf (Page 14))
David, you'll have to answer that question for yourself. Bottom line is that if you hike and camp in bear country, you might get munched. The odds are very low, statistically much lower than the odds of getting killed driving to work, but bears are remote enough from our everyday experience that they seem to be a more immediate fear. Most of the time bears are predictable, and as long as you follow the rules for cooking and food storage and try to not surprise a bear, you should have no problems. Cases like this, which seem to be the extreme exception to the rule, shake that confidence and remind us of how fragile our lives might be.
I'll still hike and camp, solo and with others, in Griz country, but thanks to this the next time I go out I'll probably sleep a little less easily.