I just started using piCal on version .6 and really like all the features it offers. One thing that should probably get added to your todo list (didn't see it in TODO.txt) is to update piCal.php's *_html() functions. Right now, there are several lines that are hard-coded with a specific date() such as line 2417. To get the dates to show up properly in my neck of the woods (USA), I had to change

} else $start_desc = date( "H:i" , $start ) ;

to

} else $start_desc = date( _PICAL_DTFMT_TIME , $start ) ;

where I changed the defined _PICAL_DTFMT_TIME to define('_PICAL_DTFMT_TIME','h:ia')