This is a Ubiquity (firefox extension) command to post to identi.ca, it's based (it's pretty much the same) in the twitter command available in Ubiquity by default.

x.js

const IDENTICA_STATUS_MAXLEN = 140;

var noun_type_identica_user = {
  label: "user",
  rankLast: true,
  noExternalCalls: true,
  suggest: function nt_idcauser_suggest(text, html, cb, selected) {
    // reject text from selection.
    if (!text || selected)
      return [];

    var foundAt = (text[0] == '@');
    if (foundAt) text = text.slice(1); // strip off the @

    var suggs = CmdUtils.grepSuggs(text, this.logins);
    // only letters and numbers, up to 64 characters are allowed as identica
    // usernames.

    if (/^[a-z0-9]{1,64}$/.test(text))
      suggs.push(CmdUtils.makeSugg(text, text, {}, 0.5));

    if (foundAt)
      suggs = [{__proto__:s,
                 text: '@' + s.text,
                 html: '@' + s.html,
                 summary: '@' + s.summary,
                 score: Math.pow(s.score,0.8)}
               for each (s in suggs)];

    return suggs;
  },
  logins: function nt_idcauser_logins(reload) {
    // TODO: figure out how often to clear this list cache.
    if (this._list && !reload) return this._list;
    var list = [];
    var token = (Cc["@mozilla.org/security/pk11tokendb;1"]
                 .getService(Ci.nsIPK11TokenDB)
                 .getInternalKeyToken());
    if (!token.needsLogin() || token.isLoggedIn()) {
      // Look for identi.ca usernames stored in password manager
      var usersFound = {};
      var passwordManager = (Cc["@mozilla.org/login-manager;1"]
                             .getService(Ci.nsILoginManager));
      var urls = ["https://identi.ca", "http://identi.ca"];
      for (url in urls) {
        var logins = passwordManager.findLogins({}, url, "", "");
        for (login in logins) {
          var x = logins[login];
          var {username} = login;
          if (username in usersFound) continue;
          usersFound[username] = true;
          list.push(CmdUtils.makeSugg(username, null, login));
        } 
      }
    }
    return this._list = list;
  },
  _list: null,
};




// based on twitter functionality from social.js
// using: http://laconi.ca/trac/wiki/API http://laconi.ca/trac/wiki/TwitterCompatibleAPI
// TODO should there also be a "share" overlord verb with
// providers "using twitter", "using digg", etc.

CmdUtils.CreateCommand({
  names: ["identi.ca", "identica", "share using identi.ca"],
  arguments: [
    {role: "object", label: 'status', nountype: noun_arb_text},
    {role: "alias", nountype: noun_type_identica_user}
  ],
  icon: "http://identi.ca/favicon.ico",
  description:
  "Sets your Identi.ca status to a message of at most 160 characters.",
  help: ("You'll need a <a href=\"http://identi.ca\">Identi.ca account</a>," +
         " obviously.  If you're not already logged in" +
         " you'll be asked to log in."),
  author: {name:"jmora"},
  homepage: "http://identi.ca/jmora",
  license: "MPL1.1+ || GPL2.0+ || LGPL2.1+",
  preview: function(previewBlock, args) {
    var statusText = (args.object ? args.object.text : '');
    var usernameText = "";
    if (args.alias) {
      usernameText = args.alias.text;
    } else if (args.as) {
      usernameText = args.as.text;
    }
    if (usernameText[0] == '@')
      usernameText = usernameText.slice(1);
    
    var previewTemplate = (
      "<div class='identica'>"+_("Updates your Identi.ca status ${username} to:")+"<br/>" +
      "<b class='status'>${status}</b><br/><br/>" +
      _("Characters remaining: <b>${chars}</b>") +
      "<p><small>"+_("tip: If you know how to use the twitter command this is the same.")+"</small></p></div>");
    var truncateTemplate = (
      "<strong>"+_("The last <b>${truncate}</b> characters will be truncated!")+"</strong>");
    var previewData = {
      status: <>{statusText}</>.toXMLString(),
      username: usernameText && _("(For user <b>${usernameText}</b>)"),
      chars: IDENTICA_STATUS_MAXLEN - statusText.length
    };

    var previewHTML = CmdUtils.renderTemplate(
                        CmdUtils.renderTemplate(previewTemplate, previewData),
                        {usernameText:usernameText});

    if (previewData.chars < 0) {
      var truncateData = {
        truncate: 0 - previewData.chars
      };

      previewHTML += CmdUtils.renderTemplate(truncateTemplate, truncateData);
    }

    previewBlock.innerHTML = previewHTML;
  },
  execute: function(args) {
    var statusText = args.object.text;
    if(statusText.length < 1) {
      this._show(_("requires a status to be entered"));
      return;
    }

    var updateUrl = "https://identi.ca/api/statuses/update.json";
    var updateParams = {
      source: "ubiquity",
      status: statusText
      //dont cut the input since sometimes, the user selects a big url,
      //and the total lenght is more than 140, but tinyurl takes care of that
    };
    var me = this;

    function sendMessage() {
      jQuery.ajax({
        type: "POST",
        url: updateUrl,
        data: updateParams,
        dataType: "json",
        error: function() {
          me._show(_("error - status not updated"));
        },
        success: function() {
          me._show(/^d /.test(statusText)
                   ? _("direct message sent")
                   : _("status updated"));
        },
        username: login.username,
        password: login.password
      });
    }

    var login;
    var alias = args.alias;
    if (alias && alias.text && alias.data) {
      login = alias.data;
      sendMessage();
    } else {
      login = {username: null,
               password: null};
      if (alias && alias.text)
        login.username = alias.text;
      sendMessage();
    }
  },
  _show: function(txt){
    displayMessage({icon: this.icon, title: this.name, text: txt});
  }
});