dopps, that doesn't work assuming you play by the rules.
"So get that taxable UTMA into a 529 before the minor turns 21!"
UTMA funds need to be spent for the benefit of the beneficiary. Getting it into the 529 cannot reclassify it where there is the potential that the funds are not for the benefit of the beneficiary. Going to a regular 529 would allow the account owner to easily change the beneficiary, effectively stealing the money from the minor. Clearly that is not legal.
"...it then will be converted to a regular 529 once the minor comes of age--but the account owner remains intact and so too does his control of the 529."
http://www.savingforcollege.com/articles/should-you-open-an-ugmautma-529
"And when the current beneficiary reaches the age of legal ownership, he or she will have the right to contact the 529 plan administrator and take direct ownership and control of the 529 account. "
Bottom line, if the UTMA is going to a 529, legally it needs to go to UTMA 529 and the beneficiary retains the same rights upon turning 21.