It is my opinion that VLAN hopping attacks are hugely overrated. This does not mean that you should not deploy very well understood operational procedures to reduce/eliminate the risks of this attack (i.e. do not never ever use in your access ports the same VLANID that you are using for the native VLAN on your 802.1q trunks. As a corollary, never use VLAN 1). What I'm trying to say is that from the perspective of someone who wants to attack you, there are others layer two (L2) techniques that are far more reliable and with far more impact than a VLAN hopping attack.
Attacks to the ARP protocol for example are extremely simple to deploy and if your switches do not offer any kind of protection against it, the attacker can cause great damage. If your VLAN is small then your exposure is huge, if your VLAN is big, then your exposure is mega-super-huge (I have customers whose whole corporate network is a huge VLAN, but that´s another issue).
Then you have attacks to the stability of your LAN through the use and abuse of the Spanning Tree Protocol (yersinia is the de-facto tool for this). Also extremely easy to deploy and with a great impact to your infrastructure.
If your "standard" hacker cannot exploit ARP or Spanning Tree or DHCP it is my experience that he will "move to"/focus-in other parts of your infrastructure (DBs, Web, DNSs) before trying to successfully exploit VLAN hopping.
If layer 2 security is your kind of flavor, I cannot sufficiently recommend you read the "LAN Switch Security" book from Cisco Press.