I saw this posted the other day about a new program called PushEffect by QoreFunctions. It is a program that allows you to filter an SMS that will trigger a Send/Receive in pOutlook. I don't know if it'll help you with IMAP Idle (it says it's compatible with IMAP) but it would help with those using Gmail or POP3. I used to use a similar program called Butler on the Palm Treo. The downside is that if you get a lot of mail, it uses a lot of text messages (although I guess you could configure it so only certain emails trigger a send/receive).
http://www.qorefunctions.com/