Not long ago, Microsoft had taken a stand that "existing devices" wouldn't be offered an upgrade to its significantly improved (read: actually usable) Internet Explorer Mobile 6, arguing that current hardware wasn't capable of supporting the new browser's heft. That ultimately proved to be poppycock as cooked ROMs started coming out of the oven with IE Mobile 6 goodness baked right in -- and now that Sprint's version of the Treo Pro has it even though the GSM version seemingly won't be offered an official upgrade, a whole new explanation is in order. Although it does require 128MB of RAM and a 400MHz core, we've now been told that it has more to do with IE Mobile 6's unwieldy footprint -- it's hard or impossible to bundle it into an easy-to-distribute CAB, apparently -- which makes it a better fit for an entire load of Windows Mobile than an update. Occasionally, Microsoft will freshen an existing version of WinMo with a so-called AKU, and going forward, all 6.1 devices to hit the market (including the Sprint Treo Pro, coincidentally) will use AKU 1.4, which includes IE Mobile 6. So there you have it: prior to 6.5, new devices should be rocking the updated browser, but otherwise, start scanning for a cooked ROM -- knowing the community, they shouldn't be that hard to find.