In case you are unaware, android OS smartphones have taken market share from both Microsoft and Apple, and have finally been noticed by malware creators. There is a wealth of info and potential in android smartphones- credit cards, personal info, email accounts, etc.
The malware creators also know that over 90% of Droid smartphone devices are not protected, and are easy pickings.
Personally I use and recommend Eset, but this isn't yet ready for the honeycomb 3.2 version of android. So that leaves Norton, AVG, and a few others. A-V Comparatives and certified labs for antivirus/antimalware apps are in my opinion critical to getting the best AV on the market, but the mobile android market is an unknown entity at this time. When it comes right down to it though, if an app is a poor performer on desktops (AVG, McAfee, Vipre, Spysweeper aka Webroot, etc) I doubt they will perform much better on mobile, and having subpar protection is worse than no protection at all. I am also not willing to trust my data and financial information to newcomer third party antivirus/antimalware apps which are unknowns (fake antimalware apps like antivirus 2009 that are at best absolutely useless, and at worst malware themselves come to mind). If the app doesnt have a proven track record, and back to back certifications with the top comparatives and labs on desktops, I am leery to trust them on my android mobile device).
So for me that leaves 3- Eset, Kaspersky, and Norton. While I am no fan of Norton, the lite app is free, Eset is not yet available for 3.2, and Kaspersky isn't free. For the meantime, I'll go with Norton until I can get my hands on Eset's Nod32 mobile security app.
Whatever you choose though, if your running android, you need to choose something unless of course you don't mind restoring your tablet/smartphone to its default config, losing all your customizations, docs, and paid apps in the very near future ( or worse your identity, credit cards, accounts)...