I see what you mean, Morris - I noticed the same when I didn't have kids and my friends did.
But I try really hard not to witter on about DS all the time, and I meet my friends without him, and I ask questions about their jobs and everything. Another close pre-baby friend, who has kept in touch and I see regularly, says I'm the same person as before (she volunteered the info, BTW).
My 'best' friend was always crap at keeping up with everyone else but found time to mail me most days - now she doesn't even do that. It dwindled down to one email every couple of months, generally her apologising for being rubbish lately and then promising to do better. And not, obviously, being better.
And now, nothing. I keep wondering whether to mail her, just to point out that she's gone from crap to non-existent and it's really hurtful. But then I think, why would I want to be in touch with someone who has to be guilt-tripped into returning calls? But I really want to tell her I'm hurt. It sounds pathetic and playground-ish, but this is someone who was closer than my own sister.
Is it worth it? How would I do it if I was going to?