Official announcement here:
Place Pages are a new feature aimed at making the huge variety of awesome places in Second Life easier to find by creating web pages for each inworld location that opts to show in search. Today, we’re starting a beta for this feature. All regions and parcels that have elected to Show In Search now have an automatically generated Place Page that’s visible on the web, you can check them out and share them today!
I wrote "finally", because this project has existed for years -- a Linden Lab alum told me something like this was in the production queue roughly six years ago, but never got realized. Anyway, good to have it here. Daniel Voyager has a list of test pages ready to visit now.
It's definitely beta, because Pages need a lot of tweaking to really make this an effective way to surface great SL content. The first problem is right in the announcement itself: "Places rated General will be visible to anyone, and those rated Mature or Adult will be subject to the usual Maturity controls." Trouble is, most great Second Life locations are rated Mature or Adult. So in other words, hardly anyone including and especially non-users will be able to even see these web pages.
Seriously. Imagine you're a fan of HP Lovecraft who wants to show another Lovecraft fan the Page of Innsmouth, a great Second Life sim devoted to the horror author's work. If they're not already a user, here's what they get: