I've had the same complaints, there were issues with scrolling on mobile and tablet devices. My install is the latest nightly build (30/09/12) rather than 0.8.1, but I've tested it with 0.8.1 as well and it works fine, you just need to delete the /program/.htaccess file (otherwise the browser won't be able to access the mobilefix directory containing the js and css files).
It uses iScroll 4 to add one-finger scrolling, jQuery Mobile to make messages open with a single tap and it disables the preview pane (just gets in the way if you're opening messages with a single tap). It also fixes up the message view; the margin-right attribute of the leftcol div caused a massive amount of whitespace to be shown (on mobile devices) between the message and the attachments (rightcol div), I changed it so that the attachments are shown above the message.
The fix adds an is_mobile() function to /program/include/rcube_template.php, and calls the function in the constructor to see if the end-user is on a mobile or tablet device, if it is then it loads up all the js and css files in the mobilefix directory.
The files needed are in the .zip attached. Make sure you do a diff if you've got any local changes to rcube_template.php.
Possibly not the cleanest fix, but it should do the trick. Hope it helps!
