It will be supported on ZenCart's next version of software.
Regarding ZenCart, I think that it has some advantages over OSC but the most important is the fact that OSC's last version was released last year sometime and ZenCart is always updated.

I have installed ZenCart several times. Not bad, I would say. But osCommerce is better :-) The only reason I had to offer ZenCart to the customer - his hosting provider had register_globals turned off in php.ini settings and osCommerce requires this option be set to 1 (on). So, ZenCart is good only for this occasion. Just in case some hoster looks at my post - I want to say: turning register_globals will not increase the security level much...

Regards.

You are so right about that variable.
Regarding ZenCart, I admire the way they keep updating it. I am still using OsCommerce but let's face it, if it weren't for those people who create OSC contributions, ZenCart would have been much better by now. I gave a small example with ikobo but I am sure they are working on a much greater pallette of features.

And what is the process of raising limit for the merchant account? Do I have to send the documents?

I did raised my limits once. After I sent my required documents I had to wait for 18 hours to have ikobo raise my limits, so in other words, it works. There were no incidents. So, to answer your question, you have to send some documents. You can find more about this subject, if you visit http://ikobo.custhelp.com

I also found some information as to the merchant verification (add credit card, then call my bank to find the out the charge made by ikobo and enter this amount in my ikobo account). But if I send the documents, do I need to pass the verification as well?