As far as I can tell, no, there is no easy "official" way to upgrade to KDE 3.2 at this time. You could install 10.0 RC1 (but if you do that, Mandrake suggests that you uninstall KDE 3.1.x first, which does not bode well, imo). The install will also upgrade your kernel and a number of other things, but this is a Release Candidate, not a final, so it still contains bugs and in general it is not necessarily worth upgrading your entire distro with a beta just to get KDE 3.2.
Alternatively, you could upgrade from the Cooker (unstable) repository (most likely uninstalling KDE 3.1.x first is also recommended if you do it that way). Insofar as Cooker is mostly frozen (as Cooker will become 10.0 when released), this is relatively
safe-- except that as work continues on finalizing 10.0 the package revisions are changing often, so dependencies may be a bit broken (fixable, but again, is it worth it?).
A third alternative would of course be to uninstall KDE 3.1.x and compile KDE 3.2 from source from KDE.org. Bleh.
The easy but unofficial way is to add Bluehawk's repository to your Software Media Manager (url can be found at Mandrake Linux Package Sources
, and then update normally using RPMDrake. Don't know if KDE 3.1.x should be uninstalled before using that repository, but I would "think" not.