A report from Techradar states that Amazon may be in talks with Google to sell the Nexus 7 tablet. According to an Amazon spokesperson, "People higher up in Amazon are talking to Google regarding the Nexus 7."
Since we don't know who initiated the discussions, it is difficult to really gauge much from the report. Even though the Nexus 7 is said to be the biggest threat to the Kindle Fire, both Amazon and Google know that the tablet market is still relatively under-penetrated among mainstream users. Since market expansion is the primary goal of both companies and since it also stocks the iPad, it may be logical for Amazon to stock the Nexus 7 as well. This move may also lend credence to the rumors that shipments of the upgraded Kindle Fire have been delayed until later in Q3.
If Amazon does end up selling the Nexus 7, it is likely to be the 16GB, $249 version. Stocking the 8GB version is less likely as it would require Google & Asus or Amazon to break-even or make a razor thin margin on device sales. That would be a fairly unlikely outcome, but not entirely out of left field if both companies are serious about moving the market away from the iPad.