From the official release announcement:
Changes with nginx 1.1.1 22 Aug 2011 *) Change: now cache loader processes either as many files as specified by "loader_files" parameter or works no more than time specified by "loader_threshold" parameter during each iteration. *) Change: now SIGWINCH signal works only in deamon mode. *) Feature: now shared zones and caches use POSIX semaphores on Solaris. Thanks to Den Ivanov. *) Feature: accept filters are now supported on NetBSD. *) Bugfix: nginx could not be build on Linux 3.0. *) Bugfix: nginx did not use gzipping in some cases; the bug had appeared in 1.1.0. *) Bugfix: request body might be incorrectly processed if client used pipelining. *) Bugfix: in the "request_body_in_single_buf" directive. *) Bugfix: in "proxy_set_body" and "proxy_pass_request_body" directives if SSL connection to backend was used. *) Bugfix: nginx hogged CPU if all servers in an upstream were marked as "down". *) Bugfix: a segmentation fault might occur during reconfiguration if ssl_session_cache was defined but not used in a previous configuration. *) Bugfix: a segmentation fault might occur in a worker process if many backup servers were used in an upstream. *) Bugfix: a segmentation fault might occur in a worker process if "fastcgi/scgi/uwsgi_param" directives were used with values starting with "HTTP_"; the bug had appeared in 0.8.40.