Thanks for the tips, guys! it is a cheapo Walmart knockoff, and it would be easy just to replace the whole thing. I do like to repair stuff where possible, I figure it is a way to learn things. Since the hose has threaded connectors at both ends, I think i will try the heatshrink route, and report back.
One reason why I like the walmart units is that the hose unscrews from the bladder and the mouthpiece, which facilitates cleaning it.
I will report back.

I believe platypus has special repair-patches: http://www.rei.com/product/619859

I think those are just for the bladder...I'm not sure they'd work on the hose. I've never used them though so I'm not 100% sure.

For just a dollar more you could get another hose complete with a new bite valve:
http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442592483&FOLDER%3C%3Efolder_id=2534374302699815&bmUID=1210858197563

Buy a new tube and sell the old one on eBay as a slow drip plant irrigation system...

hi guys,
thanks for all the responses! I let the whole thing slide for a couple of weeks. The aquarium sealant was $9 per tube, and heat-shrink wrap was at least $15 at the electrical supply place, so I passed on them.
I decided to try using teflon plumbing tape, covered by duct tape, over the hole in the hose. It mostly worked, only leaking a few drops. then I discovered that the bladder was leaking from around the cap, so I trashed it.

john