Yes, but as lifeasabeach noted, that is part of how OS X manages memory. You'll always have inactive memory and if the OS or an application needs it, it will be allocated it. In other words, it's memory that is reserved for the application that was using it but if it is needed elsewhere, it will be re-allocated. Thus, as I said earlier, it is for all intents and purposes "free memory." Do not count that as used memory.
You've got 5.12GB of memory being used (wired + active). Given what I calculated above, that's reasonable. You've got a whole host of processes that I can't see in that list but the processes that I can see are collectively using 3662.5MB or 3.58GB. It's possible that the remainder of the processes open are using 1.52GB of memory.
I think the OP gets that point by now.. or at least hope so. But I think that there's something being overlooked and it's something that those in the "That's just how OS X handles memory and there's nothing wrong with it" camp, have never been able to be open minded about. If you look at the original post, t4ggs states that he/she has 8 gigs of physical RAM. That's quite a lot, especially given the small amount of apps running.
It doesn't matter that Safari is a pig, nor does it matter that half the RAM is being allocated in some way, active or inactive. There's still plenty of free RAM to go around, and t4ggs is saying that he has to reboot often because things slow down too much. IMHO, there's something else going on, but I'm not sure that this behavior is due to available RAM or an app which is hogging the system, or something else.
I won't rule out memory handling until they figure out what is eating system resources and such. I'd perhaps suggest systematically leaving specific apps out of the equation until things return to "normal".
1. Download Firefox or Chrome
2. Do a hard boot, total system shut down and restart.
3. Use the new browser for a while and continue other operations as you'd usually do.
3. Problem persisting? Reboot again and try not using a regularly used app, see what happens. Are there any apps starting up in your "Login Items" under "users and groups" in System Preferences? Get rid of them if so.
I've been running an extremely stable 4 year old MacBook Pro that initially had 2 gigs of RAM (updated to 4 by me) and I use resource hungary apps regularly. Photoshop, Lightroom, Aperture, Garageband, etc.. and my system never hangs or gets very slow. When it does, I quit said apps and things get better immediately. I started with Leopard, went to SL then Lion and things have always been the same.. very stable. I only ever install the OS clean, never on top of the old one.
But could it be memory handling? Again, I wouldn't totally rule it out... but I'd look elsewhere first.
Doug