iPhone 4 and iPod touch (2010), with iOS 4.1, can now upload HD video directly to YouTube. Previously, under iOS 4.0, iPhone 4 videos would be compressed down to SD when uploaded to YouTube. 4.1 fixes that. Just tap the action button at the bottom right and share HD straight up to YouTube.
The process is as simple as checking the HD option on the YouTube upload screen. Note, however, due to file sizes a Wi-Fi connection is required on iPhone 4. (No 3G HD uploads).
If you've tried it out, let us know how it works for you. For more, check out our complete iOS 4.1 walkthrough.