Constant propagation and similar issues

I'm sure your aware of these limitations, but I'd thought I'd mention
them just in case, and to see if you have plans to sort them out:

I have a query of the form:

SELECT * FROM .... WHERE (now()-date1) > 'interval 1 day';

..i.e. all rows 'older' than 1 day.  This could be efficiently
processed using the index on date1, but sadly pg doesn't know this ;-(
This transforms an operation which should be O(1) to O(rows)....

More worryingly, when I investigated the above, I find it doesn't even
use the index for

SELECT * FROM .... 
WHERE date1 > '2000-09-11 00:00:00'::datetime - '1 hour'::interval;

...so it doesn't realise that constant-constant is constant,
notwithstanding the more complex issues that now() is pseudo-constant.

This could be fixed by constant folding, I guess; any plans for that?

Jules