I would like to start tagging my images and would prefer to not have to buy another piece of hardware. Before multi-tasking the iPhone Apps weren't very good at this. With iOS4 there are whole bunch of new apps coming to market.

If you have experience with any of them your experience would be really useful. Specifcally:

Good frequency on position updating
Ease of getting the data to a Mac from the iPhone
Ease of synching the files and adding the info to the EXIF for RAW/jpeg files - RAW being a MUST HAVE
Support for all sorts of files (multiple camera brands)
DOES NOT KILL iPhone battery