Firefox 3.5.2 released today.
There are some critical issues fixed. Upgrade now.
MFSA 2009-46 Chrome privilege escalation due to incorrectly cached wrapper
MFSA 2009-45 Crashes with evidence of memory corruption (rv:184.108.40.206/220.127.116.11)
MFSA 2009-44 Location bar and SSL indicator spoofing via window.open() on invalid URL
MFSA 2009-43 Heap overflow in certificate regexp parsing
MFSA 2009-42 Compromise of SSL-protected communication
MFSA 2009-38 Data corruption with SOCKS5 reply containing DNS name longer than 15 characters