Pushlets have been used in many (commercial) applications and demos. Below are examples I know of. If you know of other products or your product is not featured here let me know.

www.geotracing.com - real-time GPS tracing on a Google Map

www.n8spel.nl - one of several GeoTracing applications

www.senseofthecity.nl - another GeoTracing application

www.qnadesign.com - see case study for www.marketnews.com

www.rabotreasuryweb.com - pushlet-based real-time market data

mis.sourceforge.net - a software toolkit for monitoring events

www.incito.com/ftseDemo.jsp - demo displaying real-time prices from the FTSE100