For those of you who don't know, Resolver One is a unique spreadsheet application written in IronPython, that allows you to easily add functionality using the Python language. The entire spreadsheet is represented as a IronPython program which can be eyeballed and extended. Changes to the spreadsheet grid are reflected in the Python code and changes to the code are reflected on the spreadsheet grid. It's really neat. Resolver is great for people who want to develop complex spreadsheets in a clean, powerful and testable way. It's also useful (and fun!) for programmers when prototyping.
One of the Resolver developers Andrzej, has written a nice article describing 5 Reasons To Try Resolver One. Of course there are more than just 5 reasons :) If you do try out Resolver One, make sure to check out the Resolver Hacks site too.
The 1.0 release of Resolver One is the result of over 2 years of work. Having joined the team very recently I've only been part of the very last bit of that. One thing I've found really interesting is the time leading up to the release date. Compared to other commercial software projects I've worked on the atmosphere felt under-control and (almost) relaxed. It seems that the XP development practices used by the development team are really paying off. No horrible integration issues right before the release, no unexpected bugs on release day, no huge schedule blow-outs. Such a nice difference.