A simple Google search reveals a wide range of free Twitter viewers. It's tempting to throw one on a projector and call it a social media solution. A deeper inspection of these options highlights crucial challenges for digital out-of-home (DOOH) implementers. Twitter allows you to create applications and services on user-generated content by exposing a rich API (Application Programming Interface). There is a lot of content available through this interface, but reaching it can be problematic. The most obvious way to receive Twitter messages, or "Tweets", on a DOOH screen is to create a Flash application using this API. Flash is the de facto standard platform for interactivity in both DOOH and the broader Internet. Unfortunately, we quickly run into limitations imposed by the Flash security sandbox.1 For good reason, Twitter's cross-domain policy prohibits third-party Flash applications from accessing most of their APIs. Therefore, DOOH implementers are forced to host a proxy server to forward API requests on their behalf.2 This proxy host imposes a single point of congestion on the application: users are limited to 150 requests per hour, per IP address. Even a small DOOH network will quickly reach this limit, filling screens with outdated messages or, even worse, no messages at all. Any requests passing through this proxy will also experience additional network latency and be susceptible to outages and congestion at the hosting provider. With Twitter's blessing, it is possible to create special, "authorized" user accounts. A whitelisted account is capable of making up to 20,000 requests per hour. This is not an SLA: you should still expect to see Twitter's famous solution... in the middle of paper, and it would be prohibitively expensive. Treatment. It is already necessary to note that attention is the new currency. When a campaign reaches a critical level of traffic, the moderator's mission shifts from "is this message profane?" to “does this message deserve public attention?” This is a different type of problem and requires a different user interface. More human agents. Social media is global, multilingual, and subject to explosive growth. Any DOOH platform that uses it must allow large teams of moderators to be productive with a minimal learning curve. The problems presented here are not unique to Twitter. Brands and users are starting to expect seamless interaction across multiple channels and multiple social networks. Facebook, Foursquare, and Flickr all offer their own APIs. Each will add their own unique challenges to digital out-of-home.