Clearwire and Sprint just launched their "4G" WiMAX network in the New York metro area, along with Hartford and New Haven, CT and Tampa, FL. I've been testing WiMAX for more than two years now since its first launch in Baltimore, and I've been following Sprint and Clearwire as they cover the country. Here are 10 things you might not know about their launch.

Sprint, Clear, Time Warner, and Comcast 4G are all the same thing, so shop around. You'll see ads for Sprint, Clear, and Time Warner around New York City. They're all partners in one network, and you're getting the exact same 4G service from each company. They have different prices and contract terms. So shop around for the best deal if you're interested.

Expect speeds from 3-8 Mbits/sec down in good conditions. That's as fast as a middling home DSL or cable connection, and faster than many of Verizon's home DSL packages. Latency is longer than on DSL, so WiMAX isn't as good for gaming as wired Internet. But WiMAX is great for watching Web video, as long as you have a strong connection.

This is for home Internet, too. The 4G partners will also be selling home PC modems: big units that sit in your window, mobile Wi-Fi hotspots, and little USB sticks that attach to laptops. They're especially good for college students, subletters, and other people who move a lot. "But Time Warner already sells home Internet," you say. Yes, and this lets Time Warner sell home Internet into Cablevision's territories around New York.

There are no limits. Unlike other wireless Internet systems, the WiMAX carriers don't put a limit on how much data you can download a month. It's all you can eat. Go crazy.

Sprint 4G phones are ready to go. If you own an HTC EVO 4G or Samsung Epic 4G from Sprint, you've already been paying for 4G service. Now just pop down the "windowshade" on your phone's screen and turn on 4G. It'll work fine. Don't keep it on all the time, though, as it will kill your phone's battery. Use it when you need extra speed.

Clearwire and cable companies may start selling mobile phones, too. All of the WiMAX partners have said they want to sell mobile phones and Internet tablets in the future. So there may be even more shopping around to do.

Phone calls? That's complicated. There's no official way to make mobile phone calls over 4G, and 4G mobile phones just drop back to 3G to make calls. But Clearwire sells home voice-over-IP phone bundles that work on 4G in other cities.

Watch out for coverage holes. Clearwire is known for swiss-cheese coverage, and if you look at its official coverage map, it's much less than the entire New York metro area. And in our experience, even in some areas with coverage, weak connections mean slow speeds inside many buildings. Coverage will grow with time, of course, but make sure this works where you want it.

This isn't really 4G, but then again nothing is. Last week the ITU, the international body that decides which G is which, declared that no "4G" service being sold this or next year will actually be 4G. So 4G as we know it right now is a meaningless marketing term that anyone can apply to anything—it doesn't really mean anything.

T-Mobile's 3G can be as fast as Sprint's 4G. T-Mobile's HSPA+ system may be 3G, but in our tests last April, it was often as fast as Sprint's 4G. So if you're looking for the fastest mobile Internet connection, consider T-Mobile's G2 and myTouch 4G phones as well as the Sprint devices.