Symarctic ExtGPS is created in somewhat platform independent way. Originally, it was only created in Nokia S60 devices in mind, but it should work on other platforms which provide MIDP 2.0 API, JSR-82 Blueooth API and JSR-179 Location API.

However, there are some differences in some platform implementations. It looks like SonyEricsson has decided that the Location API's NMEA data provides only satellite information, not the actual location info. I mailed to SonyEricsson about this last year, but I never got any response.

Also, Nokia has released also Series 40 6th Edition devices equipped with GPS. At least these "feature phone" models support the required APIs:

Nokia 6700 classic
Nokia 6260 slide
Nokia 3710 fold

If anyone has tested ExtGPS on these new handsets, please post your experiences in comments!