I've just ordered a 4GB microSDHC card, investing $41.29 (+ 6.99 shipping) from:

http://tinyurl.com/387eop

and will report here whether it works in my Sprint Touch phone, which I can't wait to actually have in my hand.  There's good reason to believe it will work, because the User Manual for HTC Touch specifies "SD 2.0 compatible" as does the manual for Sprint Mogul.  The SD Association defines this specification to include support for SDHC with card capacity 4GB.  Soon, 8 gig microSDHC will become available, according to:

http://www.toshiba.co.jp/about/press/2007_08/pr2201.htm

This 4GB microSDHC already works on the original GSM Touch I have no doubt it will work on the HTC Vogue, (Sprint Touch).

I've seen the 8GB MicroSDHC already out there, and the Sprint Touch will support up to an 8GB MicroSDHC.

http://www.techdepot.com/pro/product.asp?stchg=1&productid=5699101&affid=10000485

http://www.elite-electronix.com

There's also the 6GB MicroSDHC all over the place as well.

As expected, the 4GB microSDHC card works fine.  When the price for an 8 gig becomes reasonable, I'll be guinea pig again, even though some spec sheets for this phone state support "up to 4 GB" (no such limit is shown in the User Manual nor in the Getting Started Guide).  Thanks to chicagobrad01 for links to (expensive) 8 gig cards, but what evidence is there for chicagobrad01's claim that Sprint Touch will support 8GB microSDHC?

I got the "claim" that it will support 8GB microSDHC from the Touch by HTC Fact Sheet (pdf) found here:

www2.sprint.com/mr/cmastaticfiles/non-landing//documents/NewsRelease/HTCTouchFactSheet.pdf

have not ACTUALLY tried it out myself.

Many thanks chicagobrad01, right you are.  Saw that page before, but completely missed that very important spec.  Makes me real anxious to go for an 8GB.  Maybe the holiday season will bring some doorbuster deals?

I Gue55 I'll UpDate thi5 - I Have the 8GB Micro SDHC Card and it works fine...It5 an Krazy Amount of 5torage and i'm thinkin about buying another1 ju5t for movie5...lol...and it wa5 al5o extremly affordable on EBAY...Got mine5 for 66.00 5&H Included...

The 4 gig and the 8 gig cards work great in the phones. However, there is an issue with Sprint Music on these... Sometimes, Sprint Music doesn't see the songs if they are stored on the card.