It has been confirmed by Erich Waas that head to head will may patched into the game post launch.

I appreciate the feedback on the blog. It’s great to see people passionate about ModNation Racers: Road Trip. As a gamer, if I saw a game I was looking forward to playing didn’t have a feature I wanted, I’d be bummed too. I didn’t expect everyone to read the blog and agree with me or for the blog to smooth over strong feelings on the matter. My intent was to explain the position the development team took when designing the feature set. A couple of you have mentioned that MNR PSP had online play and this is of course true. But part of the decision to not include MNR:RT at launch was that the percentage of MNR PSP gamers who played online. The percentage was in the single digits. I imagine if we said MNR PSP didn’t have online head-to-head prior to its launch, the reaction would be the same. But in the end, not many actually played online head-to-head. All this said, the development team is looking at online head-to-head in a patch. This wouldn’t be available day-1 of the PlayStation Vita launch but it is indeed something being researched as I type this.

Also I swear if IGN steals this from me again and makes it a news story I'm going to go to San Francisco and smack a bitch.