4:42pm: The Grizzlies spent the day calling around doing background work on Tayshaun Prince, according to Wojnarowski (via Twitter), so presumably Prince would be headed to Memphis if Calderon is sent to Detroit. Sam Amick of USA Today reports that the Celtics are another team in the mix to acquire Calderon.
4:35pm: If and when the deal is finalized, the Grizzlies are also expected to receive a second-round pick from the Raptors, according to Stein.
4:30pm: According to Stein (via Twitter), the Mavericks are another potential landing spot for Calderon, though Dallas is reluctant to part with Vince Carter, who the Grizzlies would want to replace Gay. Tim MacMahon of ESPNDallas.com made the case this morning for why the Mavs make sense as the third team in a Raptors/Grizzlies deal.
4:23pm: The Grizzlies and Raptors have a deal in place that would send Gay and Hamed Haddadi to Toronto in exchange for Calderon and Davis, according to ESPN.com's Marc Stein (via Twitter). An agreement hasn't been finalized yet because it figures to eventually include a third team, possibly the Pistons, that would acquire Calderon, says Stein (via Twitter).
4:03pm: Several sources tell Wojnarowski that the Grizzlies have a plan to move Calderon to a third team in the discussed deal with the Raptors (Twitter link).
3:48pm: As Tillery suggested, the Grizzlies would prefer to send Calderon to a third team in the trade scenario they're discussing with the Raptors. Ken Berger of CBSSports.com tweets that there are "several potential suitors" making a push for the point guard.
3:34pm: The Grizzlies appear to be moving closer to a deal that would include Rudy Gay, according to Ronald Tillery of the Memphis Commercial Appeal. Tillery reports that Memphis is weighing whether or not to pull the trigger on one of three different scenarios, including one that would send Gay to the Raptors. The Grizzlies have two other potential deals on the table if they and the Raptors can't reach an agreement by this weekend.
Adrian Wojnarowski is also reporting that the Grizzlies and Raptors are making progress on a potential trade. According to Wojnarowski, the two sides have discussed scenarios involving a third team in addition to straight-up scenarios. The Raptors would likely part with Jose Calderon and Ed Davis in any deal (Twitter links).
According to Tillery, in their talks with the Raptors, the Grizzlies are seeking a small forward, a draft pick, and possibly Davis. A third team may have to be involved to acquire Calderon and provide the small forward the Grizzlies are hoping to land. Darrell Arthur would not be involved in that hypothetical trade, says Tillery.
Wojnarowski adds in another tweet that the Grizzlies and Raptors are discussing the potential deal with their respective ownership groups, and could reach an agreement as soon as tonight.