FF 4.0b12 thinks my user agent is Mac OS X 10.5, when it's really 10.6

[alexis]

Hey all,

I recently tried to dowload XCode 4, which requires OS X 10.6+. The
site wouldn't let me do so b/c it detected that I was running 10.5.
I'm not.

When I went to http://whatsmyuseragent.com/ in FF 4, I got this:
"Your User Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-
US; rv:1.9.0.14) Gecko/2009082706 Firefox/3.0.14 BLNGBAR"

When I went to http://whatsmyuseragent.com/ in Safari, I got this:
Your User Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_4; en-
us) AppleWebKit/533.17.8 (KHTML, like Gecko) Version/5.0.1 Safari/
533.17.8


What's going on here? The real version I'm on is the one correct in
safari: 10.6.4