While I had no real problem configuring several machines, SoftLayer is still working through making all of this function smoothly. I asked for MongoDB on my machine but got a message later that it wouldn't work with Ubuntu 12.04, the OS I happened to choose. There are menu items on the portal for CPanel software licenses, but I wasn't given an option to buy one. SoftLayer is clearly planning on making it easy to buy extras, but not all of the dots are connected yet.
One interesting option is a "bare metal" server, also sold by the hour or by the month. I spun up one of these with two cores running at 2GHz and 2GB of RAM at a price of 50 cents per hour. These don't run in the same seemingly endless stack of virtualization, allowing them to access the I/O channels faster. This pays off with databases and other disk-bound applications.
The performance of the "bare metal" server was often better, but not in every case. In some the results were largely the same as the "painted metal," for lack of a better term. The times were about the same for the relatively linear, single-process jobs like the Batik vector graphics rendering or the Eclipse test. These are largely computational. But other tests such as the Lucene searching or the Sunflow ray tracing sped up dramatically because the code was able to take advantage of the extra cores and the better disk I/O. The DaCapo benchmarks have an option to limit the number of threads, and when I held the bare-metal machines to one thread, the gains largely disappeared.
Your results, of course, will differ just as the results from the benchmarks do. The so-called bare-metal machines are better at handling I/O operations such as writing to disk because they don't have the hypervisor adding an extra step to the interaction with the device drivers.
An example of SoftLayer's GUI. This graph shows the CPU load during testing. There are similar graphs for the full range of server performance statistics.
MongoDB in the cloudSoftLayer is seeking to bottle this advantage in a different way. The company is creating its own bundles of bare-metal machines and installing MongoDB on them on top of CentOS. A monthly fee of $359, for instance, buys a four-core machine that's ready to run. You can also purchase a support subscription from 10gen through SoftLayer. You pay for some of this expertise from the beginning because SoftLayer designed the server package with 10gen's guidance.