First, rules do allow teams to talk about trades and even agree to them informally before the trading period begins. So, it's possible the 49ers have done that during the NFL scouting combine. But the NFL trading period remains 16 days away. Teams cannot enter into binding agreements until then. We shouldn't get too worked up about potential trades until the 49ers and another team say they've reached agreement.
Draft analysts have been saying for some time that the 2013 class of college quarterbacks was relatively unimpressive. Those college prospects, by most accounts, have not changed minds at the combine. For that reason, teams needing quarterbacks have additional incentive to lineup veteran options.
Seattle's Matt Flynn could also be an option for teams, but he hasn't played much. Smith posted a 19-5-1 starting record with the 49ers over the past two seasons.
NFL Network's Jason LaCanfora reported via Twitter than the 49ers have been telling other teams they've got a trade agreement just about worked out. If so, the 49ers could be telling other teams the truth. They also could be trying to stimulate the market. There's no way to know for sure in the absence of more concrete information.