I've been trying to see if movable type can emit future events e.g. intention to attend; recording the existence of; in an interesting way.

To change the date of an event (e.g. to say when an event in the future was) I had to change the editing screen to make sure you can change the date on an edited event. Once the entry was saved, I could change the date. But it is 'authored on' date so it seems sort of wrong to abuse the semantics of it in this way. Plus for repeating events you would have to add it each time. Also you would have to do a new entry each time, not just change the old one. Anyway, I have an icalendar versionof my weblog, thanks to jos yule (I've made a couple of minor changes to his template), and an RDFical version too. Oh and what the hell, an RSS 1.0 and RDFical one, just for fun.

Here's the icalendar template, again, not really my work, but worth reposting for the differences from jos yule's version (line length, uid uniqueness and date rather than datetime, which has to have a timezone in the same file, which is tricky to do using the current mt tools):

BEGIN:VCALENDAR
VERSION
:2.0
PRODID
:-//iCalendar experiment in Movable Type//EN
<MTEntries lastn="15">
BEGIN:VEVENT
UID
:<$MTEntryID pad="1"$>@planb.nicecupoftea.org
SUMMARY
:<$MTEntryTitle$>
DESCRIPTION
:<$MTEntryBody words="5"$>...
URL
:<$MTEntryPermalink$>
STATUS
:CONFIRMED
CLASS
:PUBLIC
DTSTART
:<$MTEntryDate format="%Y%m%d"$>
DTEND
:<$MTEntryDate format="%Y%m%d"$>
DTSTAMP
:<$MTEntryDate format="%Y%m%dT%H%M%SZ"$>
END:VEVENT
</MTEntries>
END:VCALENDAR

and the RDFical template:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://www.w3.org/2002/12/cal/ical#">
<Vcalendar>
<prodid>-//RDFiCal experiment in Movable Type//</prodid>
<version>2.0</version>
<MTEntries lastn="15">
<component>
<Vevent>
<uid><$MTEntryID pad="1"$>@planb.nicecupoftea.org</uid>
<summary><$MTEntryTitle$></summary>
<description><$MTEntryBody words="5"$>...</description>
<url rdf:resource="<$MTEntryPermalink$>"/>
<status>CONFIRMED</status>
<class>PUBLIC</class>
<dtstart rdf:parseType="Resource">
<date><$MTEntryDate format="%Y-%m-%d"$></dateTime>
</dtstart>
<dtend rdf:parseType="Resource">
<date><$MTEntryDate format="%Y-%m-%d"$></dateTime>
</dtend>
<dtstamp rdf:parseType="Resource">
<dateTime><$MTEntryDate format="%Y-%m-%dT%H:%M:%SZ"$></dateTime>
</dtstamp>
</Vevent>
</component>
</MTEntries>
</Vcalendar>
</rdf:RDF>

This would be much much better if you could add some stuff about whether you were planning to go, the homepage of the event etc. I've not thought through how to do this yet. It'd be a hack. I'm really not sure there's much point in having an ical or RDFical feed for a blog unless it actually talks about events in the sense or meetings, conferences etc. You could have a blog that was just events maybe. Here's an example of mixing foaf and RDFical to talk about attendence and to give the event a homepage.