I'm hoping someone can set me straight here. I'm about to launch a site that uses sessions and url masking (mod-rewrite). Do I avoid the sessions problem by using mod_rewrite or are they totally unrelated when it comes to bots?
You gotta watch out for session ID's as far as search engines go, because they will halt most in their tracks. That's why so many forums don't get indexed past the forum index. To avoid problems with SID's and bots, don't use them where a user is not logged in, use cookies to keep track of preferences and whatnot. That way bots will never run into a URL with a SID tacked onto it. As far as static URL's go, definitely employ them. They rank higher, they get indexed far easier, they allow for URL keywords, and they're more friendly to the end user.
Find more related info about hiding session id's here: http://forums.digitalpoint.com/showthread.php?t=23427