This isn't a problem I'm seeing yet because neither I nor the school district is using Lion yet (next delivery of new MAC's):
Most systems that appear to be affected are 2010 MacBook Pros running a Core i5 or Core i7 processor and with Nvidia 330M graphics, but some iMac systems have also been affected. The problem appears to be an issue with the handling of the Nvidia graphics card, either in the drivers or in the firmware of the card, and may be rooted in how the systems are handling the switch between the onboard and discrete graphics chips in these dua-GPU systems. Affected users have found that if they force their systems to run on the integrated graphics chip then the prevalence of the crashes lessens, if they happen at all.
Read more:
http://reviews.cnet.com/8301-13727_7-20083.../#ixzz1UCLwybqs