As far as I can tell the main use for this is similar to DBLP's author profiles: a way of finding out a quick summary of what someone else has been doing lately, or of finding a paper whose author you know. Unlike DBLP, it's augmented with citation counts and h-indexes, but perhaps more importantly it includes all publications that Google knows about not just those in DBLP-indexed venues. It also allows its authors to edit the publication data for their own publications, and if some of that cleanup can trickle back to the main part of Google scholar that would be a very good thing.
Like DBLP, it includes a way of linking authors to their frequent co-authors, but that feature is sort of useless right now, at least for me, because most or all of my co-authors don't have profiles.
Another piece of control Google gives to authors is whether to keep journal and conference versions of papers separate or to merge them into a single combined entry. On the face of it this would seem like an easy way to manipulate the h-index it shows, but in my experience (at least, trying to choose mergers honestly to clean up the profile rather than merging unrelated papers) splitting vs merging makes almost no difference. If one really wanted to manipulate these scores I think a more effective way would be to find the papers whose citation count is close to but below threshold and drum up more citations for them. And if Google were serious about making the h-index harder to manipulate and more meaningful, they'd eliminate self-citations from their counts, something that should be easier to do now that authors are treated as first-class entities in their data.
ETA: Did you know that Alan Turing's h-index is only 23? That should tell you something about the value of such measures. Also, a group of people named Peter Taylor have found a clever way of scamming the system: claim all publications by similarly-named people as theirs.