Speakout Wireless pay as you go unlimited data for $10/month works for A-GPS & uploading photos to flickr on my N8 via WAP and it works beautifully. Full N8 setup details forthcoming! Setup Summary for the impatient: Nokia N8 auto configuration for WAP works; just copy the WAP access point to the Internet group and setup Application settings | Positioning to use the WAP access point for the positioning server. Haven't tested email and any other apps but I don't care :-)
There may be gotchas but it doesn't appear to require a voice value plan or any voice plan! I'll also post in a month or two to confirm whether there is any fine print to trip up on! But for now appears to be a cheap and cheerful pay as you go unlimited data plan!