Update December 2010: the new Dev version has a bug with scrolling up. Wait for 24 hours and an update will be available via tools/about/update.
With some mice and touchpads, the wheel only works in one direction (down; you can't return up). The cleanest way is to download and install a patch from this web page:
It will work afterwords. It is compatible with all versions of Chrome (2,3) that I have tested. Alternatively, you may go to the Control Panel, Mouse, Wheel, and switch from "Enable Universal Scrolling" to "Use Microsoft Office 97 Emulation Only" or something like that. Chrome will be fixed but some other places where wheel can be useful (e.g. scrolling the programs in the Vista start menu) may break.
You may write your experience with the hints above in the fast comments. It seems that starting with the real, non-beta versions 188.8.131.52 and above, released on December 11th, 2008, the bug is not there.