From the Retronauts re-release roundup for this week:

I struggle to understand how this loophole has persisted for so many years but I’m happy to report that it is still open: simply log into the Xbox Marketplace using your browser and then click on this link (and do not change the region settings on the page) and you should be able to claim a copy of Ikaruga for your Xbox for the low, low price of nothing. Be sure to download a copy onto your X360 before you put it away; it’ll sleep better, I’m sure.