I had this driving instructor long long time ago, who argued that the most dangerous time for a new driver is their second year after they get the licence. Still quite a rubbish driver with the confidence of a raging bull.
Same applies to programmers.
Above is the magic quadrant of programming abilities vs eagerness. (courtesy of Dr. Dan Spooner)
Now your average junior programmer would not do anything crazy, they usually come up with an idea, ask around a bit and get a second view before they commit any code.
Your experienced programmer is usually self motivated and low maintenance. Asks for requirements and general direction.
Ideally you want programmers to progress in 45 degree diagonal, increasing eagerness with ability.
The dangerous lot is the left top area, where the programmer is very eager to take on work but not proportionally capable. This is where people start to write crazy things like synchronisation bugs that will run fine for a long time, killing the system when you actually need it to work.
Find that geezer in your team, keep an eye on their work.
Technical stuff on programming, java, DSLs, etc...