You can right click the tab bar and choose Bookmark all tabs. That won't bookmark the same page twice (URL in location bar) though, even if they have different content.

You can also look at extensions like:

• Save Session: https://addons.mozilla.org/firefox/addon/4199
• Tab Saver!: https://addons.mozilla.org/firefox/addon/1774

OK thanks but that just bookmarks the pages - i want to be able to open them all up again at some time in the future when i am working on a certain subject. And i dont want them to open up every time i start firfox.

Found this comment on review of tab saver add on page :

For people that do a lot of inter-related research with many tabs on many firefox windows open is to be able to save a whole windows worth of tab addresses to a document to be opened later. This is needed because at some point your resources become over taxed and at best slow operation, at worst a chrash. this would allow for one page to be saved and re-opend at a time rather than closing down and saving them all, and opening with the same resource headache. you could save windows for a specific search theme seperate from other windows-search themes until resource problem is removed below resource problem threshold.

So i guess for now its not possible but it seems like such an obvious feature to include......

You can open all the bookmarks in the folder where you saved those pages (tabs) via "Bookmark All Tabs" with a middle click on that folder or via the right-click context menu of that folder (Open All in Tabs).