The Glasnost tool for checking whether a particular connection appears to be traffic managed with respect to BitTorrent traffic is not new, and Torrent users are also past masters at avoiding management too. The New York Times leads with a web based headline of "Putting the Brakes on Web-Surfing Speeds", which appears to be based solely on Glasnost testing, thus falling into the common mistake of assuming the Internet is just about web browsing.
BT made a comment to PC Pro about the 'revelation' that 74% of tests carried out on BT's British regional network indicated P2P traffic management. The spokesperson took the obvious line that the research appeared out of date, with NTL, Opal Telecom, Telewest Broadband, Carphone Warehouse, Tiscali UK and Pipex all being mentioned, suggesting the data was out of date, where upon the response from the Max Planck Institute was that the provider naming was down to 'legacy registrations', which we take to mean that IP addresses are still registered to old trading names. Attributing back to an ISP based on an IP lookup, may in the UK result in BT Wholesale White Label services being attributed to BT Retail. The traffic management carried out by BT Retail is distinctly different to any management (if any) carried out by BT Wholesale on its white label services. Providers buying IPStream and WBC services normally have their own IP blocks, but the White Label service can result in BT Wholesale handling the connection end to end.
BT Retail makes no secret that it manages peer to peer traffic at peak times, and most UK providers who employ traffic management are fairly clear it happens. The extent to which management is experienced will vary based on what other users are doing, and the fact that traffic often flows through different routes in an ISP depending on where you live.
Interestingly the original print version of The New York Times article had a different title "Slowing Broadband to Curb the Hogs" which was published on 14th November 2011. This sums up the more common reason for throttling, in that the small number of people trying to build their own video archive of everything ever made available online who queue up masses of material in BitTorrent clients and leave it running 24/7. While there are other applications that chew through masses of bandwidth e.g. iPlayer and OnLive, generally people are watching/interacting and do this for perhaps just two hours a day. The impact of P2P throttling on the apparently favourite pastime of downloading Linux ISO images is really not a big issue for the Linux community, as many distro's are also available via HTTP mirrors.
The reality of traffic management is that if it is done right, and not used purely to squeeze another 10,000 users onto an already crowded pipe, it can help ensure that peak time performance (i.e. latency) for time critical applications like online gaming and video streaming/conferencing remain acceptable. As a general rule, the first indications of a provider hitting capacity limits in a part of its network are the gamers complaining of jitter/variable latency, which given the amount some spend on gaming hardware/software you can understand them being so vocal.
The UK broadband user is lucky to some extent, compared to other countries, as the UK has a wide range of providers to pick from, and with Sky running an unlimited, unmanaged network while it attempts to increase customer numbers, the fact that other big providers use traffic management can be avoided without a massive impact on the wallet. Though past history suggests, that unlimited networks that are attractive price wise, do hit a point where bandwidth growth exceeds network investment, the great guessing game is always when will it happen.