It seems to me in the current application market, the biggest problem is obscurity. My approach will be to:
Make my applications available in an ad supported format, as well as a pay format.
This won't be a light version, the ad supported format will be fully functional, it will just have ads. I expect that because of this I won't sell many of the pay versions, but thats ok.
I also plan to write this blog about developing my applications, including source code. This will hopefully both attract attention to the applications, and increase the likelyhood of getting my applications reviewed by one of the iPhone review sites.
Of course having a cynical reason to post the blog, will hopefully also motivate me to keep the blog going, and not let it wither away.
I'm a big fan of ebooks, and one of the points made by Eric Flint about book piracy applies to my applications, the biggest problem is obscurity, not piracy. Until I achieve a MUCH greater degree of success, anything that gets more hits or downloads for my application is better.
This is especially true on the Iphone Application store, there is a huge drop off after you fall out of the top 25, and even more after the top 100 (for a given category). I'm not aiming towards the big categories, but still am unlikely to enter the top 100 unless my ideas and implementation get out there.