It is highly likely any North American GSM phone will work with Speakout, I am sure there are exceptions. So far, my vast stable of phones and devices work.

Opera is a godsend! Any application that can run through a http proxy at port 80 will probably work. The Rogers proxy is a bit annoying in that it can mess up some images, and some AJAX, but it is probably a small price to pay for a $10 a month data plan.

I doubt you would have much luck with streaming programs unless you do some nasty hacks. If you want to do email, I highly recommend you let gmail access your outlook, and then use gmail to access your mail through http. Again, nasty hacks would needed in getting outlook email using speakout.