Another take at ERCalendar. This time, it's using iCal4j to generate the data, so you can use all of the 
available APIs from iCal4j to extend it to your needs.

Sample call to create your calendar data:

  public WOActionResults createCalendar() throws URISyntaxException, SocketException, ParseException {
    ERCalendar calendar = new ERCalendar();
    
    java.util.Calendar startTime = GregorianCalendar.getInstance();
    java.util.Calendar endTime = GregorianCalendar.getInstance();
    endTime.add(java.util.Calendar.HOUR, 2);
    
    EREvent event = new EREvent(calendar);
    event.setClassification(Classification.PUBLIC);
    event.setDescription("Long description/note");
    event.setEndTime(new NSTimestamp(endTime.getTimeInMillis()));
    event.setFreeBusyStatus(FreeBusyStatus.BUSY_TENTATIVE);
    event.setLocation(new Location("Montreal"));
    event.setOrganizer(new Organizer("probert@macti.ca"));
    event.setCategories("Category 1, Category 2");
    event.setPriority(Priority.HIGH);
    event.setStartTime(new NSTimestamp(startTime.getTimeInMillis()));
    event.setStatus(EventStatus.CONFIRMED);
    event.setSummary("Title of the event");
    event.setTransparency(Transparency.TRANSPARENT);
    event.setUrl(new URI("http://www.wowodc.com"));
    event.addAttendee(new Attendee("probert@conatus.ca"));
    
    Calendar calendarData = calendar.transformToICalObject();
    ERPublishCalendarPage nextPage = (ERPublishCalendarPage)pageWithName(ERPublishCalendarPage.class);
    nextPage.setCalendar(calendarData);
    return nextPage;
  }
  
Basic Exchange support was added. It's raw right now, but you can use it like this (this sample will create a empty contact)

    URL urlToWSDL = ERXApplication.application().resourceManager().pathURLForResourceNamed("Services.wsdl", "ERGroupware", null);
    
    ExchangeWebService service = new ExchangeWebService(urlToWSDL, new QName("http://schemas.microsoft.com/exchange/services/2006/messages", "ExchangeWebService"));
    ExchangeServicePortType port = service.getExchangeWebPort();
    ((BindingProvider)port).getRequestContext().put(BindingProvider.USERNAME_PROPERTY, "youruser");
    ((BindingProvider)port).getRequestContext().put(BindingProvider.PASSWORD_PROPERTY, "yourpassword");
    ((BindingProvider)port).getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, "http://nameofyourexchangehost/EWS/exchange.asmx");
    
    MailboxCultureType culture = new MailboxCultureType();
    culture.setValue("en-US");

    RequestServerVersion serverVersion = new RequestServerVersion();
    serverVersion.setVersion(ExchangeVersionType.EXCHANGE_2007_SP_1);

    TimeZoneDefinitionType tzType = new TimeZoneDefinitionType();
    tzType.setId("Eastern Standard Time");
    TimeZoneContextType tzContext = new TimeZoneContextType();
    tzContext.setTimeZoneDefinition(tzType);

    Holder<CreateItemResponseType> responseHolder = new Holder<CreateItemResponseType>(new CreateItemResponseType());

    ExchangeImpersonationType impersonation = new ExchangeImpersonationType();
    ConnectingSIDType sid = new ConnectingSIDType();
    sid.setPrimarySmtpAddress("email@yourexchangehost.com");
    impersonation.setConnectingSID(sid);
    
    ContactItemType contact = new ContactItemType();

    CreateItemType contactItemDetails = new CreateItemType();
    NonEmptyArrayOfAllItemsType contactsArray = new NonEmptyArrayOfAllItemsType();
    contactsArray.getItemOrMessageOrCalendarItem().add(contact);
    contactItemDetails.setItems(contactsArray);

    TargetFolderIdType contactFolderId = new TargetFolderIdType();
    DistinguishedFolderIdType contactFolderType = new DistinguishedFolderIdType();
    contactFolderType.setId(DistinguishedFolderIdNameType.CONTACTS);
    contactFolderId.setDistinguishedFolderId(contactFolderType);
    contactItemDetails.setSavedItemFolderId(contactFolderId);

    port.createItem(contactItemDetails, culture, serverVersion, tzContext, responseHolder, null);
    
    CreateItemResponseType response = responseHolder.value;
    ArrayOfResponseMessagesType responses = response.getResponseMessages();
    for (javax.xml.bind.JAXBElement responseObject: responses.getCreateItemResponseMessageOrDeleteItemResponseMessageOrGetItemResponseMessage()) {
      ItemInfoResponseMessageType itemResponse = (ItemInfoResponseMessageType)responseObject.getValue();
      NSLog.out.appendln(itemResponse.getResponseCode());
      ArrayOfRealItemsType items = itemResponse.getItems();
      for (ItemType item: items.getItemOrMessageOrCalendarItem()) {
        NSLog.out.appendln(((ContactItemType)item).getItemId().getId());
        NSLog.out.appendln(((ContactItemType)item).getItemId().getChangeKey());
      }
    }
    
If your Exchange server is only accepting NTLM auth, add the following:

    ExchangeAuthenticator authenticator = new ExchangeAuthenticator("YOURDOMAIN\\yourusername", "yourpassword".toCharArray());
	Authenticator.setDefault(authenticator);