Home composting of human waste is not safe.  Commercial composting of disposable nappies is a new initiative that seeks to reduce the landfill impact of disposable nappies. There are many questions that have not yet been answered.  
Composting disposable nappies does reduce some of the landfill, but it doesn't address the other issues with disposable nappies, like the issues of chemical safety and environmental costs of the production of nappies.  Instead it adds another unnecessary cost to parents.

Questions that need to be considered:

• How much energy does it require to keep the process at the required high temperatures to kill bacterias and viruses?
• How much additional fuel is required to collect all the disposable nappies to take to the central processing plant?
• Is it safe to compost the chemical gel, and is the resultant compost safe to put on your garden?
• What percentage of the disposable nappies is able to be composted, and how much plastic and other non-biodegradables need to be landfilled anyway?