I posted in the 1Password feature request forum about integration with browsers.
Unfortunately, the response suggests that due to other priorities this isn't going to happen anytime soon.
Personally, I'd move from 1Password if another developer was prepared to do this.
It looks relatively simple (note: I'm not an iPhone developer, but I was a software developer a few years ago, so I have
some idea of what might be involved.
For an idea of how it might work, have a look at what Smile On My Mac have done with the iPhone version of TextExpander:
http://www.smileonmymac.com/TextExpander/touch/sdk.html
So, now we just need to find a willing developer who will produce an SDK for their product!