The BBC has finally unveiled its iPlayer, a kind of Sky for internet TV that's been in development for nearly four years. Once you've installed it you'll be able to download any BBC TV or radio programmes broadcast in the last 7 days, and you've got 30 days before the downloads die (unless you start watching a programme, in which case the download expires after seven days).

For now your downloads are limited to one machine, but the BBC's considering additional features such as the ability to transfer programmes to a PDA or mobile phone and "series stacking", which would enable you to download entire series without worrying about the 7-day download window.

So what do you get? Everything, it seems. According to BBC director of future media and technology Ashley Highfield, "Your favourite programmes from all the BBC's network TV channels will be available to download over the internet and watch on your PC without advertising for up to a week after transmission."

So far 15,000 people have tested the player, and the open beta is available to sign up for at the BBC's iPlayer site

YouTube integration

The BBC has big plans for the iPlayer. The corporation wants to integrate it with YouTube , so you might watch an extract online and then use the iPlayer link to download the whole programme, and it's in talks with potential distribution partners including MySpace , Bebo , AOL , Yahoo , MSN and even newspaper sites.

The player will also be available to Virgin Media cable customers, with other platforms to follow. From day one the iPlayer will also include tools to assist people with limited vision, and it will also support sign language, and support for subtitles and audio descriptions will follow shortly afterwards.