Its about as useful as its gonna get. If its based on a current chipset (X48, 780i), its ready. If its an older chipset (P35, X38), maybe not as much. There is no way to know what BIOS version is sitting on a store shelf until you get it home and hook it up.
I suppose you could look at the bios downloads themselves, read through the release notes, and see what they say. But why is this even an issue? If you're gonna spring for the latest and greatest CPU, why would you put it in an old board? If you have an existing CPU in your old board, just flash it and THEN put in the new CPU. I mean, right?