If you are not familiar with it, Google App Engine is Google's entry in the cloud, specifically a PaaS or Platform as a Service. With the Google App Engine, you get an IDE (python) to code your applications and then you deploy it to the Google cloud. You can integrate with other google services (as well as other http services) and use BigTable as a data store.
One of the limitation, IMHO, of Google App Engine is that it limited to Python. While I can do a little bit of python coding when I have to, I'm not a big fan of it. I don't see anything wrong with it, I just only have so many hours in the day and getting deep into python is not a priority for me. Having said that, I think I would rather python to Java.
What I would love to see is a truly pluggable architecture where a developer can choose his own language to interface with the app engine. Obviously, core code would need to be in the language of Google's choice but everything else should be pluggable via services or APIs. That may be closer than I thought.
Brad Fitzpatrick announced on his blog that he is working on a 20% project to add Perl to google app engine. He makes sure to be very specific that he is not on the app engine team and that this is not an app engine effort:
To be clear: I'm not a member of the App Engine team and the App Engine team is not promising to add Perl support. They're just saying that I (along with other Perl hackers here at Google) are now allowed to work on this 20% project of ours out in the open where other Perl hackers can help us out, should you be so inclined.
This is also not quite what I would like in that it is an effort to add Perl, not open it up for pluggable languages. Of course, as Brad says, the need for a hardened interpreter does require internal google effort. Still, this is a nice start. I prefer Perl to python.