And, as Reuters notes, the fact that dispensaries now operate in a gray area of the law is part of why they're ripe for organizing to begin with. There's nothing that will convince Wal-Mart or Toyota that they have something to gain by letting a union set up shop. But for a cannabis dispensary, a union offers a degree of establishment cred and political savvy (not to mention access) that your average storefront operation probably lacks.

So it's a neat effort. But the UFCW may want to manage its expectations. Leave aside the possibility that the Justice Department will intensify its crackdowns on pot businesses, or challenge the new regulatory systems in Colorado and Washington. The UFCW simply seems to have an exaggerated sense of how much employment, and therefore how many organizing opportunities, this industry could really provide. For instance, it estimates that they could eventually unionize 100,000 cannabis workers in California alone. According to a widely cited (and somewhat rosy) estimate by the non-profit analysts at See Change Strategy, medical marijuana is a roughly $1.7 billion business nationally today, and although nobody is absolutely sure, it's believed there are somewhere over 1,000 dispensaries in California. Within five years, See Change believes it could grow to an $8.9 billion business, and roughly double in size in existing markets.

That would be an impressive growth spurt, but not big enough to turn legal weed into a giant fount of union-ready employment. As a point of comparison, the Census Bureau reports that California's boring old pharmacies and drug stores generated some $22 billion in sales in 2007 (the last year I found data for). Today, all those stores employ around 77,439 workers. Granted, a fully legal and thriving cannabis industry would create jobs outside the dispensaries themselves (truck drivers and farmers, for instance). But there's also a chance that if the marijuana industry came out of the shadows and dispensaries got better access to capital, their numbers and total employment could actually shrink, as a few successful ones grew and achieved economies of scale. There are already plenty of entrepreneurs who would love to create the Wal Mart of weed.

In other words, one creative idea will only take you so far.

UPDATE: 12:01 PM

The New Republic's Molly Redden has wonderful -- and longer -- take on the UFCW's efforts that just came to my attention. It reports a key point that Reuters seems to have glossed over: While the union has organized thousands of pot workers over time, federal raids have reduced its total membership in the cannabis industry to around 500. I would say that's an illustration of why this is a high-risk, high-reward effort, except the unions are in such a tough spot already that I'm not sure they have much to gamble away.