Yahoo! Messenger would be the most useful, but I had trouble logging in until earlier today. It looks pretty much like the familiar desktop Y!M. The response on Smart’s 3G network was snappy. I was surprised when I pressed the “Send” key to send an IM, and it recorded a voice IM instead. A strange side effect is that the Y!M contacts got added to my phonebook.
Yahoo Search worked the first time. The integration with browsing isn’t seamless – clicking on a search result goes to the N70 mobile web browser, but going “back” from there doesn’t return to the search app.
Yahoo! Finance just opens the built in mobile browser, no client side code there. The to-do list is completely in the app, no network integration.
I haven’t tried the Yahoo! Go Flickr uploader. I did try the “Web upload” feature in the N70, which seems to be related to the Lifeblog product. The app connects to Flickr on a separate POST URL, and apparently uses the Atom Publishing Protocol API. To use this, you need to configure a separate login at the Nokia + Flickr page. I tried this with a 300+ KB 2MP picture. It had a timeout error. I guess the Smart 3G network can’t handle large uploads?