On the N810 MicroB has a "Tools" sub-menu that along with "Settings", "Components" (plug-ins), and "Downloads" has a sub-sub-menu called "Clear".

You are then given the options to clear "Browsing history", "Cache", "Cookies", "Passwords", or "All personal data".
We will soon see and hear if the N900's file system and the components of core applications are substantially different from the N8**'s or even the 770 for that matter... However, I doubt that an update would take features away.

So I'm pretty sure you will be able to continue your "holiday shopping" in private, if you know what I mean.