These patents are now owned by Stratasys. This image is from Ed Sells reprap forum post on Monday, November 24, 2008 . http://4.bp.blogspot.com/_fbJJp9o1UbA/SSr9UUQaSjI/AAAAAAAAAMg/sWPE-cXHjKo/s1600-h/Rolling+Y+table.jpg
There are comments on Makerbots page regarding prior usage of the concept at Virginia Tech but I haven't been able to track down the information or reach out to the people who would have been involved. http://www.thingiverse.com/thing:4056/#comments
CdnReprap Says: "Sorry to be the one to break the news, MB is not the first to do this. This was done way back in 2000 by Jan Helge Bohn, William saunders and Robert Sturges at Virgina Poly. They called it (CLM) Continuous layered Manufacturing" "That was the first part..... later down the road they used thin lexan material on conveyor drums."
Also from what I can tell the Makerbot patent pertains to having a conveyor belt attached to the build surface which moves independently from the build axis to eject the part, not a conveyor acting as an axis. From Claim 1 " wherein the conveyor is coupled to and moves with the build platform" . Not sure if this matters.
The reason I am concerned is basically Makerbot canned the project, doesn't sell it and no longer provides documentation. Everyone in the community is afraid to use the concept since it seems that Stratasys will inevitably enforce any patents they can.
I hope this helps. Please let me know what you find out.