Without getting too far into the technical nitty gritty, 1080p is a higher resolution format made up of more vertical "lines," resulting in a higher quality image. It's also referred to as "full HD" or "true high-definition" because 1080p is currently the maximum resolution that anything supports (well, almost). Beginning next week, YouTube will be adding 1080p support to its video playback options.
Of course, as with other high definition playback formats, you'll need to have 1080p quality video going in to get the proper quality coming back out. But a growing number of consumer video cameras are now supporting the true HD format, so it makes sense that YouTube would want to up the stakes in terms of quality.
Good news for videographers who've already uploaded 1080p quality video in the past, too -- YouTube will be re-encoding your videos for you to allow playback at the proper true HD resolution. They also plan to prominently feature great examples of 1080p videos in an upcoming homepage spotlight, so if you have some footage that really shows off what true high resolution can do, now is the time to upload it.
Does your video camera record at 1080p? Will you be using the new true high definition feature when it launches next week?