Yep, the last number of a Schläfli symbol tells you how many cells surround a "
peak", which are vertices for tilings, edges for honeycombs (4D polytopes), etc.
As far as how the cubes arrange around a vertex, the Schläfli symbol for the hypercube describes that as well. The last two numbers denote the
"vertex figure", {3,3} in this case. This means cubes meet each vertex in a tetrahedral pattern, which is why you get four of them. (Btw, you can read more about the
Schläfli symbol and see pictures of general {p,q,r} honeycombs in
this paper.)
Also interesting is that the Schläfli symbol for the hypercube is not unique. Other possibilities...
{4,3}x{} (cubical prism)
probably more I'm not remembering :)
Cheers,
Roice