The closing </div> tag in this Org file is placed *before* the closing
</li> and </ul> items for the *** A third item heading.

-----begin org file-----
#+OPTIONS: H:2

#+HTML: <div class="some-class">

* A heading
*** A heading that will be exported as a list item
*** ditto
*** A third item

#+HTML: </div>
-----end org file-----

Invalid XHTML at (around) line 116.
</div>
</li>
</ul>

By the way, shouldn't this be one list instead of three one-item lists?
<ul>
<li id="sec-1_1">A heading that will be exported as a list item <br/>
</li>
</ul>
<ul>
<li id="sec-1_2">ditto <br/>
</li>
</ul>
<ul>
<li id="sec-1_3">A third item <br/>

Kind regards,
Aidan Gauland

Emacs  : GNU Emacs 23.2.1 (x86_64-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2010-12-12 on brahms, modified by Debian
Package: Org-mode version 7.4

current state:
==============
(setq
 org-export-latex-after-initial-vars-hook '(org-beamer-after-initial-vars)
 org-speed-command-hook '(org-speed-command-default-hook org-babel-speed-command-hook)
 org-agenda-files '("~/uc-files/uc-work.org")
 org-agenda-include-diary t
 org-completion-use-iswitchb t
 org-babel-load-languages '((emacs-lisp . t) (sh . t))
 org-completion-use-ido t
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-export-blocks-postblock-hook '(org-exp-res/src-name-cleanup)
 org-export-latex-format-toc-function 'org-export-latex-format-toc-default
 org-tab-first-hook '(org-hide-block-toggle-maybe org-src-native-tab-command-maybe
                      org-babel-hide-result-toggle-maybe)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
 org-confirm-shell-link-function 'yes-or-no-p
 org-export-first-hook '(org-beamer-initialize-open-trackers)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-publish-project-alist '(("aidalgolland-orgfiles" :base-directory "~/doc-aidan/aidalgolland/main/"
                              :publishing-directory "~/doc-aidan/aidalgolland/published/" :publishing-function
                              org-publish-org-to-html :recursive t :base-extension "org" :section-numbers nil
                              :table-of-contents nil :creator-info nil :language "en" :author "Aidan Gauland" :style
                              "<link rel=\"stylesheet\" type=\"text/css\" href=\"/~aidan/aidalgolland/global.css\" />" :auto-preamble t :auto-postamble t)
                             ("aidalgolland-static" :base-directory "~/doc-aidan/aidalgolland/main/"
                              :publishing-directory "~/doc-aidan/aidalgolland/published/" :publishing-function
                              org-publish-attachment :recursive t :base-extension
                              "css\\|gz\\|bz2\\|lzma\\|jpg\\|gif\\|png\\|atom")
                             ("aidalgolland" :components ("aidalgolland-orgfiles" "aidalgolland-static")))
 org-export-preprocess-before-normalizing-links-hook '(org-remove-file-link-modifiers)
 org-mode-hook '(#[nil "\300\301\302\303\304$\207"
                   [org-add-hook change-major-mode-hook org-show-block-all append local] 5]
                 #[nil "\300\301\302\303\304$\207"
                   [org-add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point org-babel-execute-safely-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-export-interblocks '((lob org-babel-exp-lob-one-liners) (src org-babel-exp-inline-src-blocks))
 org-occur-hook '(org-first-headline-recenter)
 org-outline-path-complete-in-steps nil
 org-export-preprocess-before-selecting-backend-code-hook '(org-beamer-select-beamer-code)
 org-export-latex-final-hook '(org-beamer-amend-header org-beamer-fix-toc org-beamer-auto-fragile-frames
                               org-beamer-place-default-actions-for-lists)
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-export-blocks '((src org-babel-exp-src-blocks nil) (comment org-export-blocks-format-comment t)
                     (ditaa org-export-blocks-format-ditaa nil) (dot org-export-blocks-format-dot nil))
 )