Does PVC conduit need a termination bushing at a service panel?
From the NEC:  


  352.46 Bushings. Where a conduit enters a box, fitting, or
  other enclosure, a bushing or adapter shall be provided to
  protect the wire from abrasion unless the box, fitting, or
  enclosure design provides equivalent protection. 


The important part is bolded above - you need a bushing unless your fitting provides equivalent protection - that is, equivalent to the protection a bushing provides.   

You'll probably terminate your conduit in your panel with either a PVC male terminal adapter:  



or a PVC box adapter:  



I think anyone would agree the box adapter provides protection equivalent to a bushing.  

I believe it's generally accepted that a PVC male adapter does provide equivalent protection, but you might find someone that disagrees, and some of them are pretty sharp.  I usually ream them with lineman's pliers to take the edge off and do without the bushing.  

The box adapters make a great connection but since they are cemented on, they are a pain if you have to remove and replace them.