Try the Adobe TV video tutorials such as this one:
Learn Lightroom 4 | Adobe TV
And there are more here:
Learn Lightoom 4: Getting Started and tutorials and here:
Products | Lightroom | Adobe TV
The tutorials are a few minutes each, so not too much to absorb in one hit. I often replay key sections to make sure I understand the concepts they are discussing (or pause, try the same thing out on my copy of Lightroom, then return to the video).
There were also a whole set of tutorials on Lightroom 3 somewhere on the Abobe TV web-site, many of which will remain relevant (or with minor adaption should also be applicable to Lightroom 4), although they might be a little harder to find now that Lightroom 4 is bing pushed.
Currently still on Lightroom 3.6, waiting to see if the early Lightroom 4 performance problems get fixed. Early feedback on the very latest update appears to be encouraging.