To a certain extent I can answer the press side of things since I have some experience, generally DSiWare, WiiWare, etc stuff isn't covered much by the media. The releases are usually so minor and vast in quantity that it would take far too much time and effort to cover every single release. A site/publication also has to factor in whether their audience could gain anything from them covering the "smaller titles".
I tried to cover the "smaller" or lesser known stuff but sometimes the press material was written like an advertisemant so it took far too much work to get a paragraph or two "out the door". It gets even harder when you are writing for a site that doesn't want opinion based content for obvious reasons.
Niche sites that are dedicated to the App Store for instance might cover them, larger sites such as IGN, Giant Bomb, etc usually have a weekly segment where they compile the releases IIRC. I checked the usual places for any press related material but I couldn't find anything, the newest gamesas release I could find was dated April 14, 2004 which might explain the lack of coverage.
DSiWare seems like a niche market to me and it isn't very advanced on a technical level. You can't really use a lot of the traditional advertisemant venues for that stuff since the market is small and there is no way to buy content online unlike the Xbox Live Marketplace and PlayStation Network which do let you purchase content from a PC.