Many will front Tomcat with some httpd (apache), but it's not required in the basic stack. Tomcat is very efficient at serving static content, especially if you leverage the native enhancements available in APR. I've read more than one article indicating that fronting Tomcat with apache httpd to serve static content will more often than not leave overall site performance equal or worse (and I have some personal experience indicating this to be true).
I would say more common is to front with apache for load-balancing, or as a marshalling proxy for mashing together multiple sites and/or platforms (like having some parts JEE and some parts php, not pretty but not uncommon). However, when you grow in traffic to the point of needing 5+ tomcats you'll start to hit performance problems with apache load-balancing and you'll start eyeing beefier balancers (bigip, alteon, arrowhead etc) and dedicated HW SSL accelerators anyway.