The latest comScore numbers, showing Live Search holding steady, but not gaining, at 10.3% of the market share, seems to indicate that Live Search isn't succeeding. Yet as was pointed out a couple of weeks ago, a 10% share of search is a pretty healthy business, probably equating to ten billion dollars in market cap, according to some admittedly unscientific numbers crunched by Don Dodge. Why then do we care so much about market share? Does Microsoft need to do better in order to be considered successful?