It seems that Hudson (that link may not work) has some legal-type issues due to the Oracle buyout of Sun Microsystems. Apparently Sun (and now Oracle) retain some trademarks having to do with Hudson because one of the core developers did his work as a Sun employee.

If you read the above link detailing the problem it does seem that they have resolved the major issues. The one user visible change in all this is that the name of Hudson will change to Jenkins. The link above explains why.