Contextual homescreen launchers that adapt to suit each user have taken many forms. I was fond of Aviate, an app that adapted based on your location and the time of day, before it was eventually bought by Yahoo.
At this point, there is no real shortage of "smart" launchers in the Android ecosystem. Of course, we have to put "smart" in quotation marks, because there still is a void in terms of truly good products trying to do that. So when I tell you that Bento is a new entrant in this bustling market of context-aware launchers, you shouldn't ask, "do we need another one?" You should ask, "is this the one that will really do a great job?"
Bento is a venture capital-backed project that is in a semi-private beta at the moment. As I go over the app in its current state, it's important to keep in mind that it is not a finished product at this point and is not the kind of wide-release beta that you might be accustomed to.