Sure, wireless n is great and everything, but if you told me I'd be streaming media between 2 and 3x faster through Microsoft's new Xbox 360 Wireless Adapter (802.11a/b/g/n) than their old a/b/g version, I'd never have believed you.
$100ish (cheaper at retail)
If you upgrade to the new Xbox 360 Wireless Adapter from the old, 802.11g version, you won't notice any difference while gaming. But media streaming over your home network will see a legitimate speed increase.
For a moment, let's ignore Microsoft's traditionally ridiculous price for their Xbox 360 Wi-Fi adapters. Instead, let's just focus on performance.
Upgrading from 802.11g networking to 802.11n has a few key advantages: range is longer, speeds are faster and, since 802.11n sits on the 5GHz band, you won't interfere as much with 2.4GHz frequencies used by 802.11g and basically everything else in existence.
But there's one big thing that stops 802.11n from being any better than 802.11g for gaming: latency. Overall throughput may be faster on 802.11n (the pipe is bigger), but latency is really no less present than on 802.11g (it takes just as long for that first burst of water to come through). So those quick gaming commands aren't faster on n, and my multiplayer testing (Modern Warfare 2 and Borderlands...it was a real chore) confirmed it. Then again, I didn't really notice any lag over my 802.11g adapter to begin with.
Media streaming, however, is where those big throughputs pay off. Using Connect360, I streamed HD episodes of Mad Men from my Mac to the Xbox. I timed from the moment I hit play to to the first frame of video playback. And the difference was noticeable.
Buffering occurred between 2 and 3x faster, which was well beyond my expectations, despite how fast 802.11n is on a spec sheet. Clips went from taking as many as 15 seconds to playing (rounding up) to actually breaking the 5 second barrier. I'd love to have tested 1080P streaming over Live as well, but my DSL is the bottleneck in that scenario.
Yes, the Xbox 360 Wireless Adapter is still profanely expensive. No, if you have an older adapter (or you're just using some other solution), I wouldn't recommend the upgrade (nor do I think Microsoft is even marketing it that way). But it's nice to see a tangible improvement all the same.