I'm sorry if this is answered somewhere else, but if anybody has an answer, I'd really appreciate it...

I read on a website that microSD and microSDHC cards are not the same and that not all phones that accept the former also accept the latter.  does the sprint touch read these high-capacity memory cards?

Yes, since Sprint Touch specs include being "SD 2.0 compatible," this means it will work with microSD cards having capacity up to 2GB, as well as with microSDHC cards having capacity 4GB through 32GB.  At this time, max capacity available is 8GB.  But SanDisk has announced they will have a 12 gig microSDHC out sometime like mid-2008.

You are right about there being a major difference between SD versus SDHC.  The SD cards contain their own controller, but SDHC require the host device to provide a controller (making more room in the card for memory).  Being 2.0 compatible requires being able to use either SD or SDHC, and the Touch satisfies this.

I now have a 6 gig, but am seriously considering an 8, now that the price is down to the lower $80s and under $90 with shipping.  But maybe should wait for 12 gigs?  Price for 8 will surely drop when 12 gets released.  Or, could have 8 gigs NOW, here: 
http://tinyurl.com/2r3j6a

thanks for the info. bought an 8 gig and it works great.