The s//stuff/;modifystuff;print; (or alternately s//stuff/;modifystuff;eval;) formula is well worn turf for sigs. You do get props for the very sneaky 'ace' vs 'Ace' trick. Well done!

(I admit having to perl -le 'print "\u$&ace"' to convince myself that the 'Ace' would get capatalized properly with a null match.)

-Blake