TwitCasting lets you stream live video and tweet simultaneously from your iPhone

Late last year, Ustream and qik launched iPhone applications that let you stream videos from the iPhone to the web and allow others to watch them as they’re being recorded. And now there is an iPhone app called TwitCasting Live (iTunes link), which offers the same basic functionality, but is – as the name suggests – much more deeply integrated into Twitter.

The free app is essentially a live streaming app and Twitter client rolled into one. TwitCasting Live splits the iPhone screen in half, allowing you to view your Twitter timeline, update your status, access the web etc. on the bottom half, while recording (broadcasting) video on the top.

When the recording begins, you can automatically tweet out a specific URL for the broadcast (“I’m live on Twitcasting!”) to your followers who just need to hit the link to watch the live stream on the web or even on their iPhones (iPhone users won’t hear sound though). The app comes in especially handy during events, for example. After the broadcast, you can choose to save and archive the recording on the TwitCasting website.

TwitCasting Live works with both the iPhone 3G and 3GS, under Wi-Fi or 3G. Results were OK during tests with my 3G under a Japanese 3G network (I live in Japan), but naturally performance is best when using the app with Wi-Fi and a 3GS.

Tokyo-based Twitcasting provider sidefeed claims video latency is as low as 0.3-2.0 seconds in most countries, adding 750 concurrent viewers are the maximum the app can handle at the moment (although this number will be boosted to “a couple of thousands of viewers” next week).

Launched in Japan first, the English version made its formal debut during a demo event from TechCrunch Japan last week. Sidefeed says they have accommodated over 50,000 live broadcasts (80% over 3G) in the first four weeks and that they’re currently thinking about an Android port.