An Info World post as noted that Snow Leopard users might face security issues in September if Apple follows its policy and drops security update support for older versions of OS X.
Apple operates on a two year cycle for security updates and has done so for many years, nevertheless, with the huge customer base still on Snow Leopard, it might reconsider its normal policy and support three operating systems for security updates.
Apple has long been criticised for its security support cycle, with Gartner analyst John Pescatore calling it not ‘enterprise friendly’. Estimates show that at the current rate of Lion adoption, Snow Leopard would still have around 30% of all Mac users by September, so it’s not a small number.
If you’re one of those Snow Leopard users who hasn’t upgraded yet, I would highly recommend that you do so pretty quickly. Rumor has it that it will be possible to upgrade to Mountain Lion directly from Snow Leopard, so if you want to hold out until Mountain Lion is released than do so, but upgrade one way or another, as it could be the difference between a malware infected Mac and clean, healthy one.