The $mech->clone() method was not passing the cookie jar to its clone properly. Thanks to David Sainty.
The $mech->back() can fail if there's nothing on the stack to go back to. Thanks to Dave Page.
$mech->follow_link() did not complain if a link could not be found, even with autocheck on. Now it does. Thanks, Flavio Poletti.
ENHANCEMENTS
Added a $mech->form_id() method so you can look up forms by ID.
Added $mech->content_type(), because $mech->ct() is too cryptic.
Changes for version 1.51_02 - 2008-11-18
STILL BROKEN
t/local/click_button.t is still failing its tests for calling ->click on an HTML::Form object. I suspect this is an LWP change, but I haven't dug into it enough yet.
FIXES
Fixed the bad credentials API that stomped on LWP::UserAgent's credentials() method. Thanks to Max Maschien and Matt Lawrence.
The $mech->links method now finds <link href="..."> links. Thanks to H.Merijn Brand.
Makefile.PL explicitly requires Perl 5.8.0.
URI.pm has to be version 1.36 or else URIs don't get encoded correctly.
LWP has to be 5.819 or we have encoding problems.
Changes for version 1.51_01 - 2008-11-06
FIXES
Page history is now working much better. The $mech->back() method should behave more like a browser now. Most notably, it no longer restores the cookie state, just like your browser doesn't restore cookie state when you page back. It also should use much less memory.