If Lotus Foundations Server is based on a Linux kernel (which it is), then how come its inner workings are as inaccessible as the insides of a Windows executable? Consider that Foundations doesn't provide a desktop client interface - it only shows you the server screen with bits of information about DHCP and port addressing. Sure you can access the server using the Web-config screen but that interface is sealed tighter than a gnat's nostril and doesn't have a menu option to run command line Linux. It will only let you do the regular office management tasks like adding users and reconfiguring the schedule for automatic backup.
What happened to all of the Linux and Open Source ethos about Showing Unto Others what you have Figured Out For Yourselves? Why doesn't someone ring Linus Torvalds and register a complaint?
The answer is that Lotus Foundations Server provides a range of services and only some of these technologies are based on Open Source components. IBM/Lotus also provides its own proprietary code (such as Lotus Domino) within the Foundations package and there's certainly no requirement on them to expose the source code for those components.
Remember that Foundations is not aimed at the experienced Linux geeks of the world - it is a business solution aimed at the average SMB owner who really doesn't want access to the server command line and would probably prefer that their IT staff didn't use that access either. They just want their server to keep saving files and handling emails and doing automated backups the way it has always done it.
Lotus Foundations Server is an excellent investment for those customers.
On the other hand, if an experienced Linux admin is really serious about bypassing the standard Foundations interface then they will find the way to run command line Linux on Foundations. The Nitix Virtual Server (NVS) layer is a full-featured, standard Linux system running over the top of the Nitix core, and Linux experts can customize that NVS and add additional Linux applications just as they can for other Linux systems. Underneath the NVS is the Nitix core, which is essentially an embedded system with few configuration options, designed for easy configuration and highly reliable operation. If you want to get into rearranging those nuts and bolts then all of that is possible.
It's the Best of both Worlds.