Sounds as though someone jumped the gun a little here.
A UK release date of March 20 for MadWorld’s appeared in the paper edition of MCV and on Edge this morning, but Sega PR’s a little confused as to why: it hasn’t been officially confirmed to anyone, apparently.
It is true, however. The hyper-violent Wii title’s out in the US on March 10.
Go and buy it. You might get another one, then.