In a nutshell, yes and no. Depends on the patent really.
If they use the exact process, almost identical code and tools, then it could be a patent infringement.
But if they use different code, different tools, etc, they could probably argue it's not patent infringement.
Take MP3 and OGG for example. Both are music formats. Both compress music to a new format to play and listen to. OGG is open source and free, MP3 isn't, but OGG doesn't infringe upon MP3's patent or copyrights, but essentially they both do the same thing in the end result.
Last edited by trickykid; 08-21-2008 at 12:11 PM.