Flying below the radar for most North American analysts, French-based commercial open source portal vendor eXo has been very busy recently. Earlier this month marked the release of new versions of their key products, including eXo Portal, which we cover in the Enterprise Portals Report 2008.

Then last week eXo announced a new branch in Tunisia covering the emerging (but also largely underresearched) marketplace in Northern Africa.

When we started covering eXo back in 2006 the firm had a 27 employees and had just opened a US office. Today they have 70 developers have joined the growing ranks of open source projects trying to offer an alternative to Microsoft SharePoint.

eXo has also been an early adopter of Adobe Flex, which is actively used in several of the eXo products, including the beta version of the new "Liveroom" video conferencing component.

I don't pick favorites and am not saying that eXo is the "best" or "leading" enterprise portal, but in these times where the portal market is increasingly dominated by large vendors (IBM, Microsoft, Oracle) it is important to remember that the open source portal market may indeed offer you viable alternatives. Beyond eXo we also cover Apache Jetspeed, JBoss, Liferay, and Plone.