Resolver is a Rapid Application Development tool with a spreadsheet interface. Imagine a spreadsheet where you can embed Python objects in the cells. It's written in IronPython. It's commercial.
FIVEDASH is fully-featured, general-purpose, open source accounting software. It's brilliant. Competing with QuickBooks Pro has got to be tough. However, QuickBooks Pro can't possibly address the long tail of accounting needs. For instance, who's going to write tax software for Brazil? Someone can come along and extend FIVEDASH to do it. Since FIVEDASH is GPLed, they'll benefit anytime someone else extends it. It's the classic win win situation for open source. Accounting software is one thing I never thought I'd ever see someone bother doing open source, but now I see that it makes perfect sense for a company to do so.
Dragon NaturallySpeaking is speech recognition software. They code their prototypes in Python. It's used by Google 411 and Microsoft Sync.
Leo is an outline-based Python IDE. Imagine the entire project being treated as an outline with project-wide code folding. One drawback is that it leaves metadata in the code in the form of Python comments.
"Why Does Client Side Python Suck" was a lightning talk focused on improving software distribution for Python-based Windows applications. Python is a large download. The output of py2exe isn't extensible once it's downloaded. The speaker wants to treat Python as a platform and have it installed separately of the main application under Windows.