The word on PRISM is that organizations like the NSA are capturing metadata and using it as a basis for possible terrorists. Depending on whether you are talking about VPNing from your mobile device, say a laptop in a coffee shop or a company smart phone, back to the main office then all traffic that would be tracked going out of the phone/laptop would be destined for the main corporate office.
On the flipside of that, all the metadata could still be tracked coming out of the corporate internet connection.
There are VPN providers that you can pay for that allow you to choose fun stuff like an exit node in various physical locations. The benefit of this would be that the data would be encrypted and useless coming out of your personal internet connection. Though it could still be obtained at the VPN provider level.
No matter how many layers of VPN you go through, there is always going to be an exit node and they would just have to track it link by link (which according to PRISM they would have everything they would need to do so) till they get to the end.
This brings up some interesting (though slow) solutions like a TOR proxy, which allows you to pick two random other people using this and your traffic gets encrypted then sent out, received at the first middle node, this repeats for a second node, and then goes out to the final node. The exit node, where in regular plain text goes out to you destination. It then gets it's response and sends it back down the pipeline (after being re-encrypted)
The beauty of the TOR solution is that you and no one knows where the data exits. The downside is that considering they have a whole internet's worth of data, they could theoretically piece this together based on the whole of the metadata, but it would always be encrypted (PKI which is hard to bruteforce) until the very last step. The other downside is you may end up the endpoint of someone downloading kiddie porn.
Long story short, the only way you can legally avoid the PRISM spying scheme is to have a VPN connection that is outside the reach of the NSA and will not cooperate (think what thepiratebay does with copyright infringement notices) with this kind of crap.