Avast will be coming out with a mobile AV in the near future but I'm not sure which OS it will be available for initially. There is a thread in the Support section of the Avast forum here on Smart Phones and security and news you may want to keep an eye on.
Have you checked your mobile Market to see what is available to you now so that you have some kind of protection? Usually there are both free and paid versions; for example Symantec, Kaspersky, Dr. Web, and many others. Make sure you check the feedback from others PRIOR to downloading it and also check to see what information the developer gets from your phone (private information or can modify information). Some AV's tend to slow your system down more then others or conflict with certain mobile brands, so that is why I recommend looking at the feedback while doing a search in the Market.
If you don't already have a Task Manager on your phone, make sure you have that first so that you can uninstall easily in case what you download does not work out. In addition the Task Manager also helps you save your battery for things you do not need running.
Let me know if you have any other questions. Thank you.
