About all I am able to do via IR from my pager is:

SendIRText(String TextToSend, String FileName, String MIMEType)

In the sample code, the mime type is left blank so I'm not sure how it gets sent (I didn't use it either).

Running empire, I sent a variety of objects and they all look pretty normal (to my untrained eye). Here's the output from empire sans bodies.

A text file (memo):
In reply to:

Getting object..put_done() Skipped header 42
put_done() Skipped header c4
put_done() Skipped header 44

Object Name: textfile.txt
Object Description: (null)



An address book entry:
In reply to:

Getting object..put_done() Skipped header c4
put_done() Skipped header 44

Object Name: JoshHarding.vcf
Object Description: (null)



An SMS message:
In reply to:

Getting object..put_done() Skipped header 42
put_done() Skipped header c4
put_done() Skipped header 44

Object Name: message.txt
Object Description: (null)



An alert (song):
In reply to:

Getting object..put_done() Skipped header c4
put_done() Skipped header 44

Object Name: Anchors Aweigh.imy
Object Description: (null)



A todo list item:
In reply to:

Getting object..put_done() Skipped header 42
put_done() Skipped header c4
put_done() Skipped header 44

Object Name: Tasks.vcs
Object Description: (null)



A calculator forumula:
In reply to:

Getting object..put_done() Skipped header c4
put_done() Skipped header 44

Object Name: formula.for
Object Description: (null)



An application:
In reply to:


Getting object..put_done() Skipped header 42
put_done() Skipped header c4
put_done() Skipped header 44

Object Name: newapp.air
Object Description: (null)



A calendar entry:
In reply to:



Getting object..put_done() Skipped header c4
put_done() Skipped header 44

Object Name: calendar.vcs
Object Description: (null)



Looks like about half of those have a "42" header... without seeing what that is, I can only guess, but those seem to correlate to things that have a category field on the pager (with the exception of an application). Whatever it is, I don't think I really care... it seems to be sending correct file extensions so your plan of routing based on file extension sounds good to me.
_________________________
--The Amigo