Tech investor Larry Augustin does a good job of parsing the differences between building an open-source business in Europe and building one in the United States, suggesting that Europe is the better place to be to build an open-source business.
Fabrizio Capobianco, CEO of Funambol and an example of an open source-savvy European living in the United States, counters that while the European model of open-source adoption is good for the soul, the crass capitalism of American open source is better for business.
Personally, as an American working for a United Kingdom-based open-source company, I think they're both right. However, when it comes to cash, I much prefer the United States, with its emphasis on paid adoption of open source, to Europe, with its emphasis on (mostly) unpaid adoption of open source.
As I've noted in the past, however, this does not mean that companies should neglect Europe in promoting their open-source products. At Alfresco, up to 50 percent of our sales come from Europe in some quarters (though not most, as I don't like to lose or tie :-).
If, for no other reason than to hedge economic risk, it's important to build a strong European base of commercial open-source adoption, something that Hyperic, JasperSoft, and other open-source vendors have been demonstrating lately.
By the way, both Larry and Fabrizio missed one of the biggest differences between open-source adoption in Europe and the United States: legal wrangling. In the States, intellectual-property indemnification is the biggest issue that a software company (proprietary or open-source) will negotiate with prospects. In Europe? They mostly want to make sure that the code will remain open, but generally speaking, contract negotiations are much, much easier than in the States.
It's the one thing that makes paid adoption of open source a bit of a drag in the States, at least for me, since I negotiate Alfresco's contracts stateside.