It had previously been announced that the children of Michael Jackson will receive 40% of his estate with his mom receiving 40% and charity receiving 20% share. However a more complete and accurate description of the children's beneficiary rights were made public. The 40% share with Kathryn Jackson will receive is an income only interest for her life. The principle will pass on the children after her passing.
The children will each receive their share 1/3 at 30 1/2 of the remainder at 35 years of age and the rest at the age of 40. This is relatively standard for trust distribution ages.
See TMZ May 30 2010 Michael Jackson's Trust Lacks Trust in Kids.