I lifted this discussion of 2c openings from the newsgroup rec.games.bridge.  It's probably the
best overall discussion of the opening I've found thus far on-line.

From: kwalker@prairienet.org (Karen S. Walker)
Newsgroups: rec.games.bridge
Subject: Summary:  2C bidding structures

1 - What is the minimum point-count you believe you should have for
    a 2C opener?  What other requirements are desirable or necessary?
   Since most respondents use 20-21 or 20-22 for 2NT openings, they
require 22 or 23 high-card points to open 2C with balanced hands.  For
unbalanced hands, most don't rely too heavily on point-count
to make their evaluation.  Some play with a  minimum of 18 HCPs; others play with 20-21 HCPs.  From on-line discussions it appears that many will stretch their limits with a  major one-suiter, but required maximum values when holding a minor one-suiter or any two-suited hand.
2 - What is the minimum point-count or defensive strength that you
    believe should be *required* for a "legal" 2C opener?
    Specifically, would you consider opening 2C with:
                                   Never        Maybe       Yes
    xx, AKQ10xxx, AQJx, Void ?       6            8         14
    AKx, Void, KQxxxxxx, xx  ?      27            0          1
    x, AKQJxxxxx, xx, x      ?      25            2          1
3 - If you were on a committee hearing an appeal involving a 2C opener
    made with one of the hands above, would you rule that any of them
    constituted a psychic bid?   [ According to current ACBL
    regulations, it's illegal to psyche an opening that is strong
    and artificial, such as a strong 2C or a Precision 1C. ]
                                                        No           Maybe        Yes
    xx, AKQ10xxx, AQJx, Void ?         25             5           0
    AKx, Void, KQxxxxxx, xx  ?          12            12           6
    x, AKQJxxxxx, xx, x      ?              10            13           7
   Even though the first hand is a sub-minimum as far as traditional
point-count, it fits most players' requirements for a 2C opener.
Half the respondents said they would open it 2C, and more than 80%
would rule that it was "legal".
   For the second and third hands, many who answered "Maybe" indicated
that their decision would depend on the player's skill level and intent
to deceive.  They would give a novice some rope, but would assume that
a good player was deliberately psyching the call.
   Several respondents said the issue of proper system announcement was
also a factor.  If a pair routinely opens hands like the second and
third with 2C, then this should be clearly marked on their card (some
said it should even be alerted or pre-alerted).  Some who said they
would not rule these were illegal psychics said they would nevertheless
consider imposing a penalty for misinformation.
4 - What general structure do you use for responses to a strong 2C?
    In your favorite partnership, what are the meanings of responder's
    bids of 2D, 2NT, 3NT, a suit, a jump in a suit (2C-3H) ?
General structure:
   Control-showing responses                           9
   Point-count (Jacoby steps)                          3
   Other artificial responses                          2
   2D Waiting, cheaper minor second negative           8
   2D Semi-negative, 2H=notrump positive               3
   2D Semi-positive, 2H=immediate double negative      9
     (Most popular adjunct was 2S=heart positive, 2NT=spade positive)
2NT:   The most frequent ranges mentioned were 8-10 or 9-11.  Several
       said they only respond 2NT with soft values and few controls.
3NT:   The most frequent range given was 11-12, but several said they
       would never bid it, period.  Four people play that 3NT shows
       an unspecified solid suit.
New suit:  There was almost unanimous agreement that this should show
           two of the top three honors and otherwise "positive" values.
Jump in a suit:  Some play this is a solid suit; most said they had
                 either not discussed it or just wouldn't do it.
5 - What general structure do you use for opener's rebids?
    For example, after 2C-2D, has your partnership discussed the
    exact meanings of opener's rebids of 2S, 3S and 4S ?
   About half the respondents said they had never discussed the jump
rebids by opener, but many had good ideas for what they should show.
The general consensus was:
   2C-2D-2S = A 5-card suit *or* a longer, non-solid suit.
   2C-2D-3S = Sets trump; shows a long, solid suit and asks partner
              to cuebid an ace or king.  (If partner has shown a double
              negative, however, this sequence is invitational.)
   2C-2D-4S = Long, solid suit and a dead minimum.  Shows an opener
              based more on tricks than on controls and high cards.
   Also mentioned were some other interesting treatments for the jump
rebids.  Rudolf Holzner plays a jump to 3S as game-forcing and a jump
to 4S as Key-Card Blackwood for spades.  Henk Uijterwaal has what seems
to be a good solution to the tough problem of bidding strong 4441 hands
-- he plays a jump rebid by the 2C opener shows the 4441 pattern with a
singleton in the next higher suit (2C-2D-3S would show a singleton
club).  A few other respondents said all their jump rebids identify
two-suited hands.