At this point in the development of the technology it is probably best to keep the two issues separate: 1) wireless connectivity for your laptop 2) cell phone. As of today, I would not advise getting a cell phone which can also serve as a wireless modem. For a wireless modem see, for example, www.novatelwireless.com/pcproducts/index.html.

When thinking of a wireless modem there are two important variables.

As Mark points out a key factor is location, location, location. Your potential vendor has to get very specific with you about coverage for your location. No vendor covers every location yet and even in a covered area, coverage can be spotty.

When talking to a potential vendor you have to be very specific about exactly what you want to use the modem for. The people you buy the modem from will probably also be your ISP. If you already have an ISP that could be an issue. Any ISP can give you generic internet access, but if you need more than that you must ask specific detailed questions. For example, suppose you want to dial into your company's network. Generic internet access won't give you that.

I am not trying to discourage you. It is just that what you want is not a no-brainer yet.