Yeah, with the 5.50 GEN CFW and psnlover you can play online on the demo (there are some issues with it I believe). Hopefully, the only thing that will change when the actual game comes out is that you will have to "PSPo2 enable" your PSN account using the pass-code in order to go online. Sega might add a level of protection above that of the demo, but no one knows.
P.S. The plugin called PSNabler can read patches (developed by their team) which allow it to PSNable games that other plugins don't. The japanese version of PSPo2 was one of those games, perhaps they will make a patch for the english version as well!