This came up in an email discussion - we are arguing about the merits and demerits of a certain approach, and I mentioned what I thought was a drawback to a scheme. To that, my colleague replied : "Okay, we can table this, but I just want to clarify something..." after which he went on to elucidate his views.... Does that mean that the discussion is closed on this ? If so, did he mean to say "I agree to what you say, but I wasn't totally wrong either" or something similar, or is it the reverse ?
In American English, to table something means to postpone discussion on something. It might mean to postpone it indefinitely, but usually it just means that the discussion should be resumed at a later date. (As others have pointed out, in British English it means the exact opposite. Two countries divided by a common language, as someone said.)
table (v.) in parliamentary sense, 1718, originally "to lay on the (speaker's) table for discussion," from table (n.). But in U.S. political jargon it has the sense of "to postpone indefinitely" (1866). Related: Tabled; tabling.
That may be true for political jargon, but in every business meeting I've ever been involved with, to "table" something usually means the issue wasn't going to go away but that we were agreeing not to talk about it during the current meeting.
According to http://www.robertsrules.com/faq.html#12 (Roberts Rules of Order):
The purpose of the motion to Lay on the Table is to enable an assembly, by majority vote and without debate, to lay a pending question aside temporarily when something else of immediate urgency has arisen or when something else needs to be addressed before consideration of the pending question is resumed. In ordinary societies it is rarely needed, and hence seldom in order. [RONR (11th ed.), pp. 209-18; see also p. 127 of RONRIB.]
He probably was using the word casually, meaning to communicate that he doesn't think reaching a consensus is necessary or useful, and he doesn't want to continue the discussion either right now or ever.
RONR chapter 17(page 209, line 23) begins immediately with the description
To interrupt the pending business so as to permit doing something else immediately.
It is then followed by multiple pages explaining how to handle the incorrect usage of the motion, explaining how most people mean to postpone the subject, and to table is not what they meant.
It is notable that tabling deprives the minority of rights since the motion to table is not debatable; to use it to kill discussion is highly improper. The correct action to achieve that goal is to postpone(to a date or indefinitely), which does allow debate.
The correct use of tabling is to get to a matter that is more urgent with the intent to come back to the issue as quickly as possible.
To "Table Something" means to put it out in front of everyone and discuss it. Imagine Thanksgiving Dinner. When the bird is on put on the table, everyone comes and sits to eat the bird. They don't shelve it, which would mean to put it away and pull it back out later. In a meeting, to Table it means to discuss it and make a decision on it for all to have their input on it.