PowerShell (formerly MSH)
PowerShell and osh are based on very similar ideas. Both pass objects from one command to another. These objects represent various OS concepts (process, file, etc.) or useful language constructs (number, string, list, map, etc.). Both stress the use of operations on objects as replacements for text processing tools, such as grep and awk, which are often used to extract object attributes from textual representations of objects. One major difference is that osh is designed to be used from within an existing shell, such as bash; while PowerShell, due to the absence of well-developed shells in the Windows world, is a complete shell. Similarly, osh builds on a well-established language, Python; while PowerShell includes a new language. (I'm unclear on the relationship between PowerShell and other Microsoft languages.)

Cluster ssh
Cluster ssh (cssh) allows you to interact with multiple nodes simultaneously. A console is opened on each node. Whatever you type is echoed on all nodes. Very nice for working with up to about eight nodes (IMHO). Beyond that the consoles overlap or you need really tiny fonts. Also, no integration of results across nodes.

pssh
Parallel versions of ssh, scp, rsync, nuke and slurp. Written in Python.

PuSSH
PuSSH = Pythonic Ubiquitous SSH. A parallel version of ssh with options for controlling degree of parallelism, timeouts, and node selections.

PyCrust
A graphical Python shell. Haven't tried it.

IPython
IPython = Interactive Python, an alternative to the standard Python shell. Haven't tried it.