From The Register (as linked on another thread here)

"3 UK's excellent high-speed HSDPA network blankets much of the country - and you can access it from a laptop with a monthly tariff that's about the same as the price of an hour's Wi-Fi. [...] RIP, public Wi-Fi."

Only trouble is, unless I'm missing something, you can get a USB modem on that "mobile broadband" tariff for £10/month, but if you want the same tariff with a 'phone, for a bluetooth connection to an N800, you have to add the £10/month broadband option to an existing monthly contract, the cheapest of which is £15/month (and being that my average monthly mobile call bill is about £1.24, I don't care how many minutes/texts it includes).