I can't really tell what's wrong - I don't know enough about bash. app-shells/bash-completion-0.20081219-r1 works app-shells/bash-completion-1.0-r1 does not with following: 'eselect bash<TAB>' or 'svn up<TAB>' (OK, this example is silly, as 'up' is enough anyway) with app-shells/bash-3.2_p39 (on unrelated note, is 4.0 as safe as this version by now ?)
Pretty darn sure this is a fault of -r1. It installed a bash_completion.sh file instead of bash-completion.sh which in turn messed up any previous settings that you may have had. If I am wrong on the above assertion, then I am not sure. Both examples work for me. *** This bug has been marked as a duplicate of bug 265807 ***