Android ApplicationsAll the information you could ever want about Android Applications. Learn about apps and get help with them... all here! New apps can be found and announced in the Applications Announcements forum linked below.
As random as it is, I know the answer, so I registered to reply! (My Galaxy S arrives tomorrow, so I've been browsing for hints and tips early! )
Anyway, https://iphone.betfair.com/#_home works with Android. It's what Betfair's helpdesk recommends. It's only a matter of time before an actual app appears, whether it be official or unofficial. They have an API, which developers can use to place bets using 3rd party apps, so someone's sure to have a crack at it.
You can reinstall the apk file on your new Galaxy but the app is no longer available in the Android Market. Google changed their policy regarding gambling apps and pulled all betting apps like the Betfair app.
Luckly you can now download the app directly from the Betfair website. Betfair don't provide any detailed instructions on how to install the apk file but this article Installing Betfairs Android APK App explains it pretty well.
Because the Betfair native app is now a non market app you will need to make a change to the phones settings firsts which is explained in the article.