These services have their place. Instawallet is a brilliant service for introducing newbies to bitcoin. A newbie can have a bitcoin address up and running and making payments, literally within seconds. In this era of short attention spans, the Instawallet service is invaluable for spreading bitcoin adoption.

I frequently tell friends to visit Instawallet.org and quote me the address they see. Then I send some small change to that address. They immediately "get" bitcoin.