Some do mate, and not just from us. That being said, cant think of one our youngsters being loaned out ATM. Trouble is, the loans are usually to lower league teams, that might not be able to look after the lad as well as a big club can, (schooling, coaching, general growing up really), and that kind of restricts the clubs that would be suitable to loan to.
Beckham was loaned to Preston, (I think), before he broke through at Utd for example.
I think we should loan lads to clubs in the SPL more actually. Maybe set up a relationship with a club up there (I'm sure Jock would approve if some of our youngsters were playing at Dundee United for instance)