I thought you said you wanted to standardise a single library!?
Right...that's the basic idea, however there is a good reason for supplementing jQuery with Ext:
The OpenLayers library is the core of our GIS functionality & it's developer community are embracing Ext for providing enhanced UI widgets:
- GeoExt: http://geoext.org
- MapFish: http://mapfish.org
- HSLayers: http://les-ejk.cz/2008/12/hslayersmapfish-and-others/
JQueryUI just isn't functional enough of a base yet to build such functionality:
- No Layout, Grid, Toolbar