I don’t have an opinion on them one way or the other, but I’ve seen them often.
I work for a law firm (and have worked at various law firms over the past 10 years), and I’ve seen enough of them that the practice seems to be *de rigeur * at law firms.
I’ve seen them mostly in memo format (on paper), but Ive also seen those firm-wide e-mail good-byes. Sometimes, an “escapee” will just post his/her farewell message on the “things of interest” firm intranet.
And it’s always an attorney (never support staff, which is what I am) who does this. The basic outline is as follows: My time at Increase Your Billable Hours or You Can Fucking Forget Partnership! LLP has been fun/rewarding/informative, and I’d like to thank [partner to whose ass I surgically attached my lips for my six-figure paycheck], [associates with whom I competed Death Match 5000-style], and (sometimes) various support staff. I couldn’t have done it without you! You can reach me at To Hell with Your Kids and Family and Any Semblence of a Life that you THOUGHT You Had Before You Walked Up Into This Bitch. Ta-ta!
I know that I said that I didn’t have an opinion about these things, but on second thought, I sometimes find them to be humorous. It’s like, so, you’re leaving. Congratulations on the soul-sucking step up*, but, really, most of us don’t know you (apart, perhaps, from your petty, bullshit, and unreasonable demands and your jaw-dropping inability to say, “Hey, I know my document was difficult, and I know my handwriting ain’t for shit, but you guys did a bang-up job, and I appreciate it!”), so we won’t notice, and won’t care, when you’ve moved on to greener pastures.
*Yes, I realize that this is not, by any means, representative of all attorneys or law firms–and, hey, we *need * lawyers–but I’ve worked in big NYC law firms, and from what I’ve seen at the firms where I’ve worked, it’s mostly Soul-suckingville. Big time. But, hey, the annual Christmas/Winter/Holiday parties and picnic/day at the zoo/whatever’s going on this year events tend to be really nice. Free food (e.g., GINORMOUS shrimp) AND top-shelf alcohol? You are SO singing my song!