A bit of a tiff has developed around the BBC website, regarding their way of linking out.
Instead of being direct links, they link via a "tracker" (called "go"). This has caused a little bit of a hoohaa (so much so that one slightly sensationally-titled blog post at Blogstorm has got a response from the BBC itself), as the links from the site do not pass SEO benefit.
There's no denying that the BBC (and other mainstream media websites) get hundreds of thousands of views an hour, so if your page is linked to, you will likely get monumental visitors. If some of those link to you from their website (and - from my experience - they usually do), plus new readers & people aware of your blog/business or service, then that's a good thing, surely?
I had a look at a few links from two mainstream media sites - The Independent & The Sun respectively, and whilst the former did give us a normal link, The Sun didn't, slapping on a "Nofollow" tag. Not entirely sure why, my guess is that The Sun has more advertisers & sponsors, they don't want to be giving Google Juice to companies that don't advertise (It's a horrible conclusion and totally inaccurate, largely because the adverts on The Sun's site are in flash), but the BBC, The Independent & The Sun have more responsibilities to journalists & sources - they have responsibilities to their advertisers. Martin Belam explains this perfectly in this post.
However, it could also be argued that websites such as the BBC can "steal" stories, so giving something back wouldn be fair. Suppose if I wrote a blog about something newsworthy - say an initiative I'd pioneered had some council trouble and I blogged about it - the BBC would probably rank above me in that story on Google.
I believe the above cases are rare though. 99% of webmasters would take a link hidden to everybody but Internet Explorer 1 visitors viewing the website on a 320x240 screen at five past 3 in the morning from the BBC. Not because of the SEO benefit, but because the traffic (and the associated benefits associated with that traffic) is so great, that the residual benefit to your site (both non SEO & SEO ways) would definitely be worth it.
What side of the fence do you sit on? Should mainstream media sites provide searchable links or - from large sites - any link is a good link?