Hear me out after the jump...
Wizards Trade Motive:
Whether or not Washington can truly compete for a title, the team is clearly in "win-now" mode. We're over the luxury tax, have built around several aging stars, and sacrificed both picks this year to get immediate help (though the 2nd Rd Pick sale was a little less obvious to the cause). This being the case, acquiring a true defensive stopper is important for any Championship Run (read '2nd Round Playoff Run'). This much is clear by simply looking at the recent history of NBA Champs. Each of them carried a defensive stopper on the Wing who specialized in knocking down open 3-pointers on offense. This is exactly the role James Posey fills. In fact, he helped define this role with Boston in 2008 and Miami in 2006. The others are Trevor Ariza ('09 Lakers), Bruce Bowen ('07 Spurs, '05 Spurs, '03 Spurs), and Tayshaun Prince ('04 Pistons). Posey would not start as either Foye/Butler or Butler/Miller would start on the wings. But Posey would garner plenty of playing time off the bench to help slow down the likes of Lebron James, Vince Carter, Paul Pierce, Ray Allen, Joe Johnson, Dwyane Wade, and hopefully Kobe for one playoff series (not to jump the gun or anything). Dominic McGuire has somewhat of a cult following around here (I came close to buying a #5 jersey myself) but Posey's defensive prowess in itself obviates the need for Mcguire. Once you add in Posey's far superior offensive contributions he becomes an obvious upgrade. The only knock on this exchange is that McGuire can play multiple positions (which we all know had Saunder's salivating atavistically). However, this fact is not as important when you realize that several other players can wear multiple hats as well (see: Caron Butler (SG/SF), Gil (PG/SG), Foye (PG/SG), Mike Miller (SG/SF/PF), Jamison (SF/PF)). This trade would also be a good use for the expiring contract of Mike James and as a byproduct, help to alleviate (albeit slightly) the logjam in the backcourt.
*In anticipation of the "what about the future salary implications of taking on 2 more years at $6.5mil each" argument against the Posey acquisition I have a few preemptive points. First, we are very definitively in "win-now" mode so salary implications take a back seat to Championship aspirations. Second, if this move were to prevent the retention of either Randy Foye or Mike Miller's services in 2010-'11 we already have the perfect succession plan. His name is Nick Young. And even if he's not good enough to start at SG a year from now he will surely be (read: already is) good enough to garner big minutes as a backup (assuming we could retain one of the two former Wolves).
Hornets Trade Motive:
This part is a little bit simpler. The Hornets are not in cost-cutting mode by any means, but have traditionally been a low-budget franchise and reside in the smallest NBA market in the league. This trade gives them a chance to get under the luxury tax for the summer of 2010 (when Peja will no doubt exercise his $14mil player option) by taking advantage of Mike James's expiring contract. It also partially replaces Posey as the defensive presence with a young, versatile, athlete who can run the break and throw down Chris Paul alley-oops till the cows come home (...or Saints come marching?) Recent draftee, Marcus Thornton, could pick up the shooting that would be lost in the exchange as well. Finally, Mike James adds one more thing to this deal...as, you know...a real person, and not just an expiring contract. The Hornets drafted Darren Collison to groom as a CP3 backup but if they happen to make a playoff run this year they won't likely want him on the floor that soon. Mike James has plenty of experience and could be a nice bench spark for them too.
This trade would immediately make the Wizards a better basketball team both offensively and defensively yet appeals to the Hornets fiscally and developmentally. It's a classic short-term/long-term exchange that might just make a difference, however subtle, by increasing the Wizards odds of contending.