A couple of my colleagues, Brian Brown and Jeff Muendel, identified  that Flickr  has begun NOFOLLOWing hyperlinks in their photo profile pages. I’ve confirmed this and have a few more details to add.
As you may recall, I’ve previously recommended using Flickr for image search optimization , partly because it was quite beneficial for building some PageRank, and I’ve also delivered a presentation about this same concept at a number of SES conferences during the past couple of years. (As you may know, getting sites with good PageRank to link to your pages helps to grow your own site’s rankings in search results in Google and other search engines. “NOFOLLOW” is a parameter that search engines developed to allow webmasters to specify links which should NOT confer PageRank — they did this as a means of reducing incentives for unethical or over-aggressive people to spam links through blogs, comments and other sites and interfaces.)
It’s important to note that Flickr continues to be beneficial as part of a search marketing program even if they have revoked their “link love”. There’s large amounts of usage inside Flickr, and those users can click through to your site. Also, the photo profile pages are loved by Google and Yahoo, so the pages get indexed and searchers click through from the search engines to your photo pages and then can still click through to your site. Referral traffic from Flickr can be significant, depending on the type of photos you have and how well you’ve optimized the profile pages.
Jeff noted that Flickr has yet to NOFOLLOW links on Set and Collection descriptions. I also notice that links on your user Profile pages still confer PageRank, too. (You can see this on my Flickr profile page .) I don’t believe any of those pages are quite worth as much for PageRank as the profile pages themselves, but this info may be worthwhile in terms of your Flickr strategy, ongoing. I believe that the best strategy is to focus on good quality content and honest tagging and labeling of the photo pages themselves, though — don’t focus on PageRank so much as doing good quality content and deriving clicks over to your main site — an indirect marketing strategy, in effect.
I would expect that Flickr will probably circle around and revoke NOFOLLOW links on these remaining pages which don’t yet sport the protocol.
Also note: Flickr has rules in their terms and conditions against commercial use of their service. This is the most confounding aspect of understanding Flickr for potential marketing benefit. Flickr does not really define out what their acceptable use is, versus what isn’t. In actual practice, there are loads of people who have been using Flickr for advertising their business, and have been doing so for years. I can point to photographers, models, real estate agents, art galleries and many others who flagrantly are using the service to advertise and drive click-throughs to their main ecom sites. I’d previously interpreted that anti-commercial-use clause as intending to keep people from using Flickr as an image hosting platform, and turning around and charging others for hosting their content. However, Flickr does sometimes delete user accounts for just advertising their products. You should take this into account, in my opinion, and try to be very indirect in advertising your items. Photos which look like catalog photos, with backgrounds clipped out in Photoshop, and linked directly to online catalog sales pages may be more prone to getting penalized/deleted. More “natural-looking” photos are less likely to get dinged, and avoid adding commercially-oriented pics to Group photo album sets. I’ll likely write a commentary about Flickr’s inconsistent application of their anti-commercial clause in a future article.