Not sure why there was that dig at Hotmail. The throwaway address idea is great; I already have 2 separate gmail accounts I use as throwaways.
I'll justify my dig more than I could in a short news entry
When I had a Hotmail address, I often encountered websites that refused to let me register using the address because Hotmail addresses are already
considered disposable. Half the reason I switched from Hotmail to Gmail was to get away from people scowling at me when I tried to tell them I had a Hotmail e-mail address. I have never once had a site reject my registration because my e-mail address is a Gmail one, even though Gmail still costs no money and theoretically deserves no more respect than Hotmail.
Consequently, it's a bad move in my opinion for Microsoft to embrace the idea that its Hotmail accounts are disposable by literally making an option for them to be throw-away accounts. Unless Microsoft is trying to cater to spammers and hackers, I think they're better off trying to build the reputation of Hotmail than further bury it.
EDIT: As an aside, there are already many services like GuerrillaMail.com and Mailinator.com that offer this service. I'm not sure why Microsoft believes it is in their best interest to compete with them in this area.