I think another way you could look at this, which would be both easier and faster to implement, would be to enable USB host mode on your device to connect your camera directly to the N800 to upload directly to Flickr that way (still tethered to your cell phone).

Pros:
- Solution is readily available and stable
- Doesn't require purchase of an Eye-Fi or other wifi devices
- Doesn't require additional software ports to Maemo
- Would enable a multitude of other USB usage scenarios
- Cheap

Cons:
- Requires a USB OTG adapter (it's cheap though)
- Not as gee-whiz super cool wireless as a Wifi solution