Google Docs Tops Among Top Earners - News by InformationWeek

Interesting snapshot -- see the article for more details, demographics, etc. 

Google owns the market for online productivity applications, thanks largely to the affinity shown by upper income individuals for free software.

Since October 2006, Google Docs & Spreadsheets has captured the lion's share of traffic to online productivity applications, according to statistics released today by audience metrics firm Nielsen//NetRatings.

[...]

Despite the growing popularity of online productivity applications, Stewart doesn't see Google or other online office app providers threatening Microsoft anytime soon. "Eventually, Web-based productivity tools could become as widespread as traditional software from companies like Microsoft," he said, "but they clearly have little to fear in the immediate future, given the relatively low penetration numbers that we're seeing."

Source: Google Docs Tops Among Top Earners - News by InformationWeek