You can use the machine variables to read the date and as long as your clock and calendar is correct on the control, you can have this update itself daily using macros. The only trick here is that the date is a calendar and not a julian date or week number if that's what you need.
For example, if all you need to know is that today is May 13, that's what you'll get from the machine variable. However, if you need to know that today is actually Julian 133 for the year 2011, this is another issue (or any other form for Julian dating). For this, you'll need a seperate macro to recalculate the julian date based on the calendar day of the control as it changes.
For Matrix controls, the variable for the calendar is #3011. When you read #3011, the output is Yr > Month > Day. So reading #3011 today will give you a result of 20110513. From this, you need to extract what ever digit(s) you need for your engraving. The variable updates itself everyday on it's own at midnight just like any other date clock you might have at home.
For Fusion controls, the variable is the same but the output is a bit different as the year only posts the last 2 digits. So today would be 110513.
It's just a part..... cutter still goes round and round....