Despite the strength of the underlying technology (HP OpenMail, yes I'm biased), Scalix didn't seem to be making its numbers. From the reports of "13 engineers and sales support staff" I imagine that a number of people got made redundant recently.
Xandros and Scalix have been working together for a while now, so I suppose this acquisition makes as much sense as any.
Presumably Scalix now can't get sued by Microsoft for violating Exchange patents? ;-)