I know it's not a trade rumor, but this is worth a look. Derek Zumsteg, author of The Cheater's Guide To Baseball, may have uncovered some shady behavior on the part of Angels' closer Francisco Rodriguez. He's got screenshots of the mysterious substance over at his blog. Derek mentions in the comments that the Rangers complained to the Commissioner's Office after the game.
It seems that thus far, the mainstream media either didn't notice the story or chose to ignore it. Halos Heaven comments on the possibility, asking why teams didn't uncover this years earlier. The problem is that everyone affiliated with this little situation seems to root for an AL-West team, so biases may sneak through.
UPDATE: The Rangers found out about the allegations yesterday, but did not contact the Commissioner's Office. Through some other means, perhaps just by browsing the web, MLB found out about it today and is investigating.