Hudson does not check for changes all svn repositories when multiple repos are
used. It only checks for modifications in one of them. Version 1.286 and 1.287
have this bug, version 1.284 works correctly, I have not tested version 1.285.

I have setup where a Hudson job has several SVN repos:

file:///some/path/project1
file:///some/path/project2
file:///some/path/project3

Hudson polls for new modifications every minute.

Subversion Polling Log should look something like this:

Started on Mar 2, 2009 11:04:48 AM
file:///some/path/project1 is at revision 352
file:///some/path/project2 is at revision 1,150
file:///some/path/project3 is at revision 913
Done. Took 39 ms
No changes

But it looks like this:
Started on Mar 2, 2009 11:04:48 AM
file:///some/path/project3 is at revision 913
Done. Took 39 ms
No changes

It will not detect changes done to other projects.