While Sprint and AT&T were both keen to show off their branded devices at this evening's Samsung Galaxy S II event, T-Mobile's version of the phone was cloaked in a bizarre level of secrecy -- the ultra-brief press release, lack of information on availability, vague spec list, and hands-off glass box encasing the demo unit at the event all seemed odd to us. We don't have an official explanation, but we've got a theory brewing: it's got a processor that you won't find in any other version of the Galaxy S II anywhere in the world.

Why do we say that? By all appearances, T-Mobile's Galaxy S II is the Hercules that we'd scooped back in mid-May; we'd nailed the 4.5-inch display, NFC support (which Phone Scoop has confirmed this evening via the FCC), and 8-megapixel camera with 1080p video capture. Another spec we'd reported at that time had been the use of a 1.2GHz dual-core Qualcomm Snapdragon APQ8060 processor -- extremely unusual considering the availability of Samsung's own high-performance Exynos, which it's using in both the Sprint and AT&T models. And notably, Samsung has been very careful today to say only that the T-Mobile model is dual-core, but we haven't been able to get anyone to comment on the make or model of the processor.

A big part of Samsung's presentation at the event revolved around Exynos' blazing performance, so that explains their vague references to an unnamed processor here -- mentioning a Snapdragon-powered model in the same breath as two Exynos models (ostensibly with better benchmark scores) would've been pretty awkward for all parties involved. In fact, it's generally awkward whenever Samsung has to reach outside its own parts bin -- the company has been able to serve itself admirably through the last year and a half with the Hummingbird and Exynos line, and non-Samsung processors (Snapdragon and Tegra 2, namely) are rarities in the lineup.

As for why T-Mobile would've requested Snapdragon over the Exynos 4210, we're not sure. Technical data sheets for the 4210 are sparse at best, but it's conceivable that the processor isn't currently certified for compatibility with any modems that support AWS HSPA+, which T-Mobile requires. It's also possible that T-Mobile insisted that the Galaxy S II support the 42Mbps network that it's in the process of rolling out, and as AnandTech points out, the Snapdragon would do the trick when paired with Qualcomm's MDM8220 modem -- the Intel XMM6260 found in the European S II (and possibly the AT&T model as well) tops out at 21Mbps.

Sure, the phone could also use a Tegra 2 -- Samsung has done it before, and T-Mobile has done it with the G2x -- but in light of the accuracy of our Hercules details so far, we're holding our line on the Snapdragon rumor. Hopefully, these guys don't take too long to start serving up more details on specs and launch; the Droid Prime may not be far off, after all, and we don't want the S II to get buried that fast.