It's now over two years since a few underground song-swapping services put peer-to-peer technology firmly at the forefront of the IT agenda. Napster's little bout of legal trouble, which kicked off back in December 1999, ground merrily on throughout 2001, but P2P has largely outgrown adolescent distractions like music. Distributed computing is set to play a crucial role in the future of Internet-based computing. A look back at some of the more significant P2P stories of 2001 shows that -- although not a new concept -- P2P is starting to assume a very important role in the corporate space, as tech giants scramble to succeed in this new market. Tech sector veteran Ray Ozzie is planning to take on the might of Microsoft and Lotus with his Groove Networks venture. Ozzie, who developed Notes when he worked at Lotus, has now come up with a P2P groupware product. Groove will let staff collaborate through shared messages, documents and forums and -- unlike server-centric Outlook and Notes -- virtually all the processing and storage overheads are placed on the PCs of individual users Ozzie's involvement in P2P, like that of Intel, is seen as a safe indication that this is a serious technology. In February Intel released its Peer-to-Peer Trusted Library -- software that allows developers to create secure P2P applications. The company has also taken an interest in developing industry standards and, like Microsoft, its workforce has been using P2P applications for some time. Distributed computing is important to Intel because it involves many individual computers sharing their collective process power and data. Companies that currently invest in large mainframe computers could decide to run important simulations using P2P instead -- and that might mean buying new Intel processors. P2P also attracted attention from those with more destructive tendencies. The appearance of a proof-of-concept worm travelling around the Gnutella network showed that peer-to-peer networks were susceptible to virus attack. Once a PC was infected, this worm would monitor traffic on the Gnutella network. When it detected a file request, it would pose as the song that was being searched for -- and thus propagate between computers. Scientists at Oxford University made better use of the massive potential programming power that distributed computing offers. Well in excess of one million PC users are helping with their search for a cure for cancer, which -- like that old favourite, the SETI project -- harnesses spare CPU clock cycles. United Devices, Intel and the US National Foundation for Cancer Research are all involved in the project. Distributed computing is also a favourite of the US Army, which is attracted by the idea of wirelessly linking its soldiers together and creating a virtual network. It believes this would allow soldiers could share information much better when involved in combat situations. Such a system could also be used in training situations. Soldiers wearing head-mounted displays could take part in simulations, and could even rehearse a mission while "in the field", possibly as little as 10 minutes before carrying it out for real. Meanwhile, back at the courthouse, Napster and the record labels were engaged in a legal tussle that appears to still be far from resolved. Attempts by the song-swapper in April to introduce filters to prevent copyright-protected songs being exchanged were slammed as "disgraceful" by a federal judge, and by July it had been forced offline. It took until September for the basis of a deal to be hammered out. This arrangement saw Napster paying $26m (£18.2m) to settle part of its lawsuit, giving it the chance to relaunch in 2002 as a legal royalty-paying subscription service. But, in December, Napster and the labels were back in court arguing over how this new network would be policed. Into the void leapt Wippit, the UK's own legal P2P music-sharing system. Wippit subscribers got the chance to download as much music as they like for £50 per year -- a fee that has currently been slashed to a meagre £20 to tempt users on board. Wippit, however, hasn't yet managed to secure a deal with any of the five record labels, so its offering doesn't really compare with the heaving table of goodies that Napster once provided. A cynical soul could suggest that the majors are keen to ensure the success of their own online music services, and thus control the delivery mechanism as well as the content. Rumours abound that the European Union might take action to make sure that Pressplay and MusicNet don't restrict opportunities for independent sites should stop anything too anti-competitive from happening in 2002. One area of P2P that saw plenty of development in 2001 was instant messaging. Many Yahoo! IM users will have lost count of the number of new versions they've downloaded this year, giving themselves the chance to throw snowballs and blow kisses at online chums. Those animated backgrounds are pretty nifty too. AOL also released an upgrade to its ICQ client, while Microsoft built its IM service into Windows XP. Corporations are already concerned that IM, like email and browsing, might not be totally conducive to efficient work. They've probably already lost this battle, though. With users already realising how useful IM can be for file swapping, its popularity looks it set to boom in 2002. Rather like the rest of the P2P sector, really. See ZDNet UK's Christmas & New Year Special for our look at the tech world in 2001, and what's coming up in 2002, plus a shopping guide with reviewers' best buys. See the MP3 News Section for the latest on everything from MP3 players to Napster and the other music swapping services. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet news forum. Let the editors know what you think in the Mailroom. And read other letters.