I have no doubt this topic has been discussed on many SEO forums before but I’m going to give my take on it based on what I have experienced.
The “Google Honeymoon” as I call it, is the period 24-48 hours after producing a new web page where it first ranks in the Google search index. In my experience for the next 2-4 weeks the page will rank particularly highly and then drop back to whatever is normal for the website.
When I first publish a new article in this blog I generally receive a first page rank for the keywords in the title and possibly the tagged internal keywords too. Generally if the search term isn’t uber-popular I can hold the number 1, 2 or 3 position for a few weeks and then it drops to somewhere around positions 4-10. Bear in mind this blog has a high PageRank and good authority so it ranks quite well, what is considered normal for your blog or website might be pages 3-10 with a brief stint on the first or second page during the “honeymoon”.
For periods of time I’ve had top three rankings for terms related to the articles I have recently published, including keywords such as Mike Filsaime, Butterfly Marketing and Rich Schefren, clearly keywords that have some competition if not from the guys themselves than other Internet marketers.
You SEO fanatics can correct me if I am wrong but I believe the honeymoon period occurs so Google can collect data on how relevant your pages are for those keywords. If during the honey your pages are clicked often and the visitor hangs around for a while (doesn’t click back and choose another option from the search results) then your drop after the honeymoon isn’t significant. The logic being that your page offers a good answer to the question being asked. If your page doesn’t get many clicks or people don’t stay around then after the honeymoon you can expect your page to drop further in the index.
As I said I’m only speculating on this, but the pattern definitely occurs for me on this blog. It’s certainly fun to watch initially while the honeymoon is on and I’m happy with how well my site ranks in general, but it’s always a bit of a let down when you lose a first position ranking. By being aware of the honeymoon you can at least understand why you might suddenly lose your rankings, though of course it’s foolish to ever believe you can be 100% certain of what Google is doing.