The smart people here will start adding CACert patching software to their products that work with their hosting, such as free FTP and Telnet programs. Far be it from MS to get hit with the same tactic for altering the settings of browsers they don't own.
Besides, the incentive for MS to add the cert to IE is the same reason they finally supported PNG images... They are always playing catch-up to Netscape/Mozilla, even though they have infinite more resources. If you see Mozilla support even "considered", IE will come running. That, and the more sites that use CAcert, the more they will be pressured to support it. Take Ev1servers... if the majority of us used them, that's a large chunk of websites that IE wants their millions to be compatible with.
Then again, that's maybe too much logic to expect from the one-size fits all MS-opoly.