Well, if you were trying to access Wikipedia's "standard" (non-mobile) site from a web browser today, you were out of luck, as shown above and detailed here. If you used the (free) Wikipedia Mobile iOS app (or, it seems, accessed the Wikipedia mobile site), however, you could continue to get Wikipedia information:
Regardless of whether you agree with their decision to blackout their browser-accessed pages today, I encourage you to consider the value they provide, and if you are financially able, to contribute. Personally, I value the fact that they provide a great deal of useful text information adorned with a minimum of images, that they cover some topics (e.g., random items from pop culture -- Hot Wheels (TV Series), anyone?) that are not found in more conventional information repositories, and they do not run ads.
