Truphone was easy to setup (Alec Saunders has a nice post about it) if you are familiar with WiFi on series 60 phones (getting much closer to something normal people can use!) and I verified it works with my land line. Nokia put the VoIP software in all of your WiFi phones not just the N80i!
I encountered a minor bug when trying to add $5 USD to my account with PayPal (PayPal worked but the redirect back to Truphone's site failed! Cheese Louise, it's 2006 why is ecommerce so hard!) but other than that it looks like a solid product.
Now the real test: cheap calls to Holland, and maybe even China and South Africa.
If you want to check it out call +13604880717 or better yet get an E61 or N80i and call me for free via Truphone!