If you're not familiar with "secondment," a British-derived military term for temporarily transferring someone from one regiment to another, the time is nigh.  In law-land, the context in which it matters is firms "loaning" partners or associates to clients for interim tours of duty.  Why?  Well, for example:

• a public-company client just spun off a division which all of a sudden finds itself without a legal department;
• an established client finds its legal department abruptly, but temporarily, short-handed (think maternity leave or short-term disability);
• either the client or (less likely, OK) the firm wants to establish a closer relationship.

Financial arrangements vary, and the article discussing this is next to opaque on the topic (for starters, it's unclear whether the client's payments cover the direct costs of the firm's lawyer), but secondments appear to have revived in the 21st Century after being commonplace in the 1960's and '70's (before in-house corporate departments bulked up) and after having essentially died out in the 1980's and '90's.

Two observations:

• Essentially every firm cited in the piece is California-based (UK firms aside, that is); and
• A commonly cited fear is that sending an associate to a client is an invitation to poach the associate.

Observations:  (1)  With this as with so many trends, California initiates, the country follows (I lived in Palo Alto for three years while at law school, so I can claim personal knowledge); and (2) Why on earth would a firm not be delighted if a client "poaches" an associate?  Won't they then be a client for as long as that alum has influence?