When you run your bank’s online banking website as an isolated application in Fluid, it should theoretically (though I haven’t tested Fluid much) make it impossible for your session details (banking usernames, passwords, transactions) to be intercepted or compromised by any type of malicious scripts which may be running in any other browsers or on the pages you access as part of your day-to-day browsing.

While this is much less likely to be happening on a Mac than on a PC (security through obscurity), isn’t it better to be safe than sorry when we are doing things like online banking? And why not your email as well, if you have accounts that are very important to you?

Mozilla’s Prism (and hopefully Fluid too) are great ways to create SSBs and thereby add one extra level of security to your online transactions. You could go even further and add an OS virtualization layer (even on a highly unsecured Windows PC, a virtual machine running only a site-specific browser running only your webapp is a secure environment for your sensitive data). But all the hassle of that solution might not seem worthwhile.

Using a SSB is a good compromise that anyone could employ for better web security.