H1B Visa (stamped) expiring next year Jan 15, extension applied and in process. I travelled to India in Nov 14 with a return date in Dec 14. I didn't expect extension would be approved before my return but it did get approved. I asked my employer to ship the approved petition to India. I carried it along with me and presented at port of entry. Officer updated my new I-94 date per approved extension petition.
If I couldn't have presented the approved extension at port of entry, my I-94 would have been given based on visa stamp on passport, which will be a problem. And I would need to contact CBP office (I guess) to request for manual I-94 update.