Sadly, the test is for 2,000 lucky Android users only, with a wider rollout promised for an unspecified future. Foursquare tested a comparable feature called "Radar" two years ago, but killed it after "Radar" killed battery life.
Google Now has by far the best proactive interruption in the business, if you have an Android device.
Google Now grabs information about you from Gmail, Google Search and elsewhere, and uses that data to improve results.
Lately, Google has folded in some amazing capabilities. For example, it preemptively feeds you information about your car rentals, public transportation information based on guesses about where you might want to go, movie tickets and sports scores.
Google Now tells you more information about whatever's on screen. It knows what you're watching because, with your permission, it listens to the sound of the show to figure out what you're watching.
Google Now is great in every way except one -- it doesn't give you enough information. Leaving Google Now running gives you a mostly static view, with "cards" coming in very infrequently.
Field Trip, another Google product, is wonderful only because of what it promises, not what it delivers.
We learned recently that Field Trip was originally designed for Google Glass but shipped on the iPhone while Glass was still in early development. It's now available on Glass.
Field Trip has the right idea, popping up contextual data. However, these are based on a list of arbitrary database-oriented websites, such as "Historic Detroit," "Public Art Archive" and " San Francisco Architectural Heritage." Unless you're in a major city, Field Trip contextual information is slim pickins.
There are other services that claim to interrupt with contextual information. But in my experience these require launching the app and refreshing it -- a conscious choice followed by deliberate action, which is the opposite of what's promised in this category -- interruption.
Looking at these few examples, the industry overall seems hesitant, unwilling or (most likely) unable to meet the promise of interruption for contextual information.
It's true that this category is fraught with hazard. People feel their privacy is being violated when a gadget demonstrates what it knows about them. It's an irrational concern because not letting the user take full advantage of harvested data (as is the case today for most users) doesn't equal privacy, just ignorance.