When viewing an item/article in a category with the Social Bookmarks enabled the Twitter button is using the wrong title tag. When the Twitter button is displayed it has a "Add to Technorati" title tag. I found the error in the item.php file;
components/com_k2/templates/articles/item.php
line 235
<li><a class="twitter" title="<?php echo JText::_("Add to Technorati"); ?>" href="
twitter.com/home?status=Currently reading <?php echo $this->item->socialLink; ?>" target="_blank"><span><?php echo JText::_("Add to Twitter"); ?></span></a></li>
