PiCloud (http://www.picloud.com/) is an offering for Python.

http://www.akshell.com is another one, although it doesn't fit under any of the headings since it's a JavaScript platform that doesn't use Node.

I think Joyent's Node.js cloud service should probably be added, considering that's where it's being actively developed right now.

Windows Azure isn't just .Net. There's Ruby, Python, PHP and Java.

http://www.microsoft.com/windowsazure/interop/

[edit] I've just thought, the Ruby and Python support might technically be through .Net via IronRuby and IronPython, but I'm not sure. This certainly doesn't apply to PHP or Java though.

This list is missing the excellent ep.io.

Can't believe I forgot about ep.io! I added it to the list, thanks :]

Andy, if you would, please add us NodeSocket. We are a node.js hosting platform for developers.

Two more:

1) http://apps.jgate.de based on AppJet, runs JavaScript apps and CouchDB (open beta)

2) http://cloudno.de based on Nodester, runs Node.js apps and CouchDB (private beta)

Great list, added some suggestions to your comments.

For Twitter users, I made a list of PaaS offerings here: http://twitter.com/peakscale/paas/members

Howdy Tim. If you would, please add us @nodesocket. We are a node.js hosting platform for developers. Gracias!

There is another solution called Bitnami cloud (http://bitnami.org/cloud) that is not in the list.

Perl Cloud at Phenona http://www.phenona.com/

I believe Windows Azure is considered PaaS.