My husband found the info on wikitravel.org It said if you have a stamp from Israel, Jordan or Egypt you will be denied entry. We flew into Jordan from Israel.
Wikitravel? You can ignore that safely, then.
I've been to Egypt on the very same PNR as to Lebanon, and it wasn't an issue at all. Immigration officer (very friendly, by the way) specifically asked ONLY for Israel Visa, which I denied - and was welcomed in. Beirut was a great stay, even if too short.