The BBC has launched the beta version of its iPlayer service. The on-demand media player means you can 'catch-up' on programming from the last seven days.

According to the corporation, only a fixed number of people will be able to sign up, with more people allowed to join during the remainder of the year.

The iPlayer has courted controversy over recent weeks as it is Windows XP-compatible only for the moment. That's because the DRM technology used to enforce a 30-day storage limit on programmes isn't cross-platform compatible and is even different to that of Vista. There were also suggestions 10 days ago that the iPlayer wouldn't launch because hackers were getting a little too knowledgeable about the DRM.

Mark Taylor, the head of the Open Source Consortium, told the BBC earlier this week: "They reiterated their commitment to platform neutrality, specifically mentioning Linux, and welcomed our offer of help to establish a cross-platform approach."

"We are committed to making it as easy as possible to use BBC iPlayer. Developing a version for Apple Macs and Microsoft Vista is absolutely on our critical path," said Ashley Highfield, director of future media and technology, last month.

"We're also committed to making it available on the television screen, which is why we are delighted to be working with Virgin Media towards a launch on cable later this year. We are hopeful that other TV platforms will follow soon after." A review of the iPlayer's progress will take place every six months.

The player uses very similar technology to Channel 4's 4OD , Sky's broadband download service and ITV's online media player. Siemens and VeriSign have delivered the Kontiki Broadband Delivery Service software that enables users to install the BBC iPlayer application on their PC, download, store and play programmes on-demand.

Jana Bennett, director of BBC Vision, said: "This is a significant moment, as it heralds a new era when viewers will have the freedom to watch programmes from the BBC's linear TV channels when they want.

"It's a revolutionary service which offers audiences more value, because from now on they never have to miss out on their favourite programmes - or those that they didn't previously have the opportunity to try."

The iPlayer began testing as far back as 2003 in the guise of the iMP (Integrated Media Player). Subsequently the technology had to go through a Public Value Test (PVT) where the BBC Governors (now the BBC Trust) had to decide if it was worthy of public expenditure. Around 15,000 people have so far used the service.

Registration for the iPlayer Beta is available now , but be warned, invitations are limited. The BBC plans to open up the iPlayer to make it widely accessible across the corporation's website as well as via YouTube. The BBC also hopes to sign up other distribution partners such as MSN, Yahoo and MySpace.

The BBC is also planning to offer streaming on demand as well as series stacking in future.

Also see How to make the BBC iPlayer multi-platform and our feature: BBC iPlayer will change your viewing forever