O2 makes it pretty difficult to get upgrades, at this time.
However, you can install another carrier's version of 6210: http://www.blackberryforums.com/viewtopic.php?t=1995
Just make sure you delete your VENDOR.XML file.
Also, keep in mind you cannot upgrade your 6210 to BlackBerryOS 4.0 unless you have 16 megabytes of memory. To find out, open your BlackBerry battery cover, remove the battery, and check the label at the bottom of the battery compartment. If it says "6210-16M" then you're all set.
Alternatively for a quick software check, go to Options->System and if "File Total" (not File Free) is well above 10,000,000 then you certainly have one of those 16megabyte 6210's.