Best Buy Platinum Series HTC EVO case is definitely rebranded (and cheaper) Seidio II Innocase
I don't know if there was any doubt about whether Seidio's Innocase cases for the HTC EVO would be rebranded by Best Buy, but here's photographic evidence that the cases are identical. So if you're thinking of buying Seidio's Innocase II Surface Combo case ($49.95), you may want to get Best Buy's Platinum Series EVO case with holster ($36.99 at my local shop) instead.
I'll have a review up before Best Buy opens its doors for the EVO release tomorrow, so you can decide whether you want to grab one of these cases while you're there.
Incidentally, you can see from my receipt that the case's SKU, 9943582, is identical to the "HTC EVO 4G Case with Holster (Black) – Platinum Series" item on the leaked Best Buy accessory sheet I showed you last week. The handwritten price was $34.99, which may or may not be accurate at your local Best Buy. Hawaii, where I live, is notorious for markups.