
I bought a 2gb Eye-Fi Explore SD Card from eBay a few weeks ago. It arrived in a sealed pack sitting inside its own USB connector. When I plugged it into the PC it was instantly recognised, but when it fired up the browser to connect me to eyefi.com to register and configure the settings it told me that it had a known fault and it was impossible to register, configure or otherwise use. Doh!
However, the site captured my name and address and committed to send a replacement f.o.c. within a few days from the States. This replacement duly arrived and I was able to register it straight away and configure it.
(Config is about telling it your router's WEP key, setting up a directory to dump pictures into when it's near youe network and giving it your Flickr (or similar) login details should you wish it to automatically post stuff there. You can also input your Twitter details so that it sends you a DM to let you know when it's started uploading photos and when it's finished.)
If you don't want it to automatically send all you pictures to Flickr you can configure it only to upload photographs that you have "protected" in your camera's settings.
Once you're configured, you just need to set your camera so that it doesn't automatically switch itself off after a couple of minutes and, provided you're within range of your network it starts uploading your pictures.
In theory, provided your camera is on, it should start uploading pictures whenever you're in range of an open wifi network but I've never experienced this and remain to be convinced.
Anyhow, the Eye-Fi card works fine in my little Fuji Finepix Z20fd. However, I was also hoping to use it in my old trusty Canon EOS 300D, which actually takes Compact Flash cards. So when I bought my Eye-Fi card I also bought a converter so that I could slide an SD (or SDHC) card into a CF shaped adaptor and use it in my Canon. The good news is that the adaptor works, in that I can take photographs and they are saved on the SD card. However, the automatic upload functionality of the Eye-Fi card don't seem to work whilst it's in the Canon even if I set it so that it doesn't switch off automatically and where I opt to 'protect' selected frames.
A point to be aware of is that it does takes a long time to transfer the photographs from my Fuji, so if you take a lot of photographs like me do opt for the 'protect' option and be selective about which ones you want to upload in this way. Either way, it's a real battery drainer. I always carry two spare batteries with me along with the one in the camera and I've sat and watched it drain all three and still not be finished uploading.
Given that I've not really seen it work on an open wifi network, I'm only using it at home and, frankly, it's quicker, cheaper and greener to take the card out of the camera, bang it into the PC and whizz all the pics across in seconds/minutes than go through all of this palaver. It would be useful if I could set it up to recognise networks at friends', family, the office etc, but to configure this I'd need to input all the individual WEP keys and, as the config is done on the laptop, I'd need to trail it round to everywhere to set it up before I ever might want to upload from the camera 'in real life'.
So on balance, I like the Eye-Fi card in principle but they're expensive (£80ish) , faffy and, given that SD cards are pretty cheap, I don't think they currently offer huge convenience or represent value for money (but I'd love other's views - @spooons?).
Furthermore, chatting to @documentally about them, he tells me that a friend of his had some problems with one breaking inside his camera... the plastic does seem a tad more brittle than a conventional SD card... so if you're going to have a dabble... take care.