Summary then is as follows:
- USA - buy kindle or nook and use free 3G connection.
- Rest of world - buy an ereader that supports wifi and pay for wifi in coffee shops etc. Buy an ereader that supports bluetooth and use a phone that can give you data access over bluetooth with a suitable subscription to pay for it all.
- alternatively don't bother and just keep reading your ebook.
Speed of ereaders isn't really an issue - if they can browse over a wifi network then they can browse over any other type of network. Screen refresh rate will be annoying but I guess that will improve over time. I assume intermediary servers will give faster / more text based access to popular web pages.