I just noticed that Isotope244 has posted a new Atomic Cannon Pocket beta on their website (that supports VGA under WM5). Link for info and demo
here.
To get my full version (since I registered it already) I just changed the link from my serial number request email from Atomic-Cannon-PPC.exe to Atomic-Cannon-PPC-Beta.exe and that worked (though no official word from I244 has hit their announcement lists regarding this as of this posting).
I'm not sure what else has changed in the new beta.