As I'm sure many of you know, the current SDHC spec will only allow cards up to 32GB. At CES 2009 the new SDXC spec was announced which will allow cards to theoretically have capacities up to 2TB. This doesn't seem to have been addressed anywhere yet, and I'm surprised more people aren't curious, but will SDXC be compatible with current SDHC technologies like our ITs? My understanding is that SDXC is just a spec change, (along with using exFAT by default) not a physical hardware change, so it seems like only a software update would be required for IT compatibility? I really have no knowledge of the technical side of SDXC so forgiven my ignorance, the research I have done so far has yielded little information.

See this thread for details, but the gist of it is Linux has supported "SDXC" ever since SDHC support was added, now it's just a matter of dealing with exFAT.

Oh well that's good to hear, so being able to use SDXC cards won't require any kind of hardware modification? And why not just use ext2/3 or continue to use FAT32 which supports up to 2TB anyway and not worry with exFAT?

Well, the primary reason behind nobody using Ext3 like they should is that they need maximum compatibility with Windows, and it'll be a cold day in hell before Microsoft natively supports Ext2 or 3. Until they're either no longer the dominant game in town, or they start natively supporting Ext2/3, we're all stuck with Fat. I know a lot of companies would love to go to a free, open source file system, but so long as Redmond is king, that ain't happening anytime soon, as much as we'd like it to.

We'll know for sure once real SDXC cards materialize but most probably no modification (HW or SW) is needed.
Yes. That's exactly the plan. Well at least until future exFAT linux filesystem driver becomes better option.

no device i tried it on supported that #$%&@¤€½¾ m@deby$h!t file system
not even m@ke$$h!t devices can use it, as they don't have mSD slots >¦-)))))))))))
was able to format it to FAT32 on my N8 but i didn't get a 64GB SDXC card to have one partition on it
missed testdisk back then, though
and it didn't show on a se7en pc neither
SDXC went back to supplier for replacement
should get another one in a couple days
FAT32 (for automatic mount's sake) ext3 for backing up of system files & swap seem good choices
and yes, N900 can handle 64GB on a SDXC device

are you sure about m@ke$$h!t devices?

not sure why i'm feeding a troll, but heck...
where? SkyDrive cloud?
(from Detailed specifications for the Nokia Lumia 900)

i presume, like everywhere, there are a couple m$ devices out there with a mSD slot...
from the ~4 millions m$ devices sold in 2nd quarter most probably where non-upgradable Darkness devices