I’ve complained about the (old) Oracle ATG Commerce licensing scheme in the past, and I can’t express how happy I am that they have introduced a new licensing structure.  Moving away from the old core or processor based licensing, to a new metrics based strategy is a huge step forward.
The new licensing is based on the volume of requests, and sold in 500,000 segments.  The setup is based on the peak number of requests in a day.  So if on the highest traffic day, say Cyber Monday, your site does 2,900,000 requests, then you need to have purchased six 500k license blocks.  Endeca Search and Experience Manager are also licensed with the same approach: request based and sold in 500k bundles.Oracle-ATG-Commerce-and-Endeca-Licensing-Model-webreadyHow-to-calculate-Oracle-Commerce-Licenses-Costs-webready
The advantages with the new licensing scheme are that it completely frees up the hardware, infrastructure, architecture.  You can run as many servers, in as many environments, as you like.  You can also  use Cloud/VMs.  This opens the door for Disaster Recovery and Active-Active availability solutions. Or multiple geography specific clusters.  Slower applications can deploy as much hardware as is needed.  And it paves the way for utilizing modern and future core heavy CPUs.
The thing to be aware of is that the requests are not user page requests, but any and all requests that are handled by the DAF Pipeline.  That includes AJAX requests, web services, and in some scenarios may count page/fragment includes.  This may push application design away from Web 2.0, AJAX heavy, style of web application that has been popular lately.  It also encourages aggressive caching.
Overall the new licensing scheme is a huge step forward and opens many interesting doors.  Good developers will need to keep the request metric based pricing in mind, but shouldn’t let it drive sub-optimal application design.