Agreed, for a developer praising itself doing so much for the MOD community Valve could try a little harder to keep them informed. Not by doing the testing for them, but perhaps a mailing list (or so) which gives notice along the lines of "We changed a few things there and there so you might wanna check compatibility".
Erm...there is a mailing list...it's called the HLDS mailing list and comes in linux & windows flavours depending on what server software you're running. You can get the details of it here:
http://list.valvesoftware.com/They gave an hours notice that an update was coming, but gave no details of what was changing.