In the past, estate planners have frequently recommended the use of trusts for this purpose, but new tax legislation – effective from 1 January 2010 – could change that.  The new law provides

for any unused part of your current estate duty deduction (R3.5m) to be rolled over to your surviving spouse’s estate, i.e. the final deduction will potentially be R7m - even without the use of a trust.

That certainly doesn't mean that trusts are dead - they will always be essential estate-planning tools in particular situations. Take advice on what to do in your specific case; and have your will reviewed at the same time.