lightenup, you might consider flagging the need to update in the thread title, if that can still be edited. It's easy to miss, and not everyone running SMC will necessarily even click on the topic.
Good idea, done.
I updated to latest git version. Can we found out which of the "new" or "old" block chain we're mining when we find blocks?
If the older version overwrites the newer, REORGANIZE messages with high disconnected blocks should appear in your debug.log. Another indicator is that you lose mined coins. If the newer version overwrites the older, then everything stays 'normal'.
Each time someone from the old version updates and joins the new version, he or she resynchronizes the two block chains. If the older has been faster, the newer is overwritten (from the split/fork point). -> At most the mining efforts starting from the update are lost.
Currently, the network hashing power of the newer version is rather large (about 6 MHashes/sec), we are at block height 100 941.
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now is a good time to update (see https://bitcointalk.org/index.php?topic=182430.msg2102353#msg2102353).