the latest version of Eclipse still does not support Tomcat 8, but you can add the new version of WTP and Tomcat 8 support will be added natively. To do this:
Download the latest version of Eclipse for Java EE
Go to the WTP downloads page（http://download.eclipse.org/webtools/downloads/）, select the latest version (currently 3.6), and download the zip (under Traditional Zip Files...Web App Developers). Here's the current link(http://www.eclipse.org/downloads/download.php?file=/webtools/downloads/drops/R3.6.0/I-3.6.0-20140213154746/wtp4x-I-3.6.0-20140213154746.zip).
Copy the all of the files in features and plugins directories of the downloaded WTP into the corresponding Eclipse directories in your Eclipse folder (overwriting the existing files).
Start Eclipse and you should have a Tomcat 8 option available when you go to deploy.