With Google's (reverse algorithms) having a Web Page spidered and Cached during a 404 error will not effect SERPS ... but for Inktomi Algos - more emphasis on Bodytext & less frequent spidering - it could mean a drastic loss or SERPs unless you have the PPI option.... Because the results affect both Yahoo and MSN it could mean a real long suffering period until the page is respidered! Has this happened to anyone with high traffic from Ink sites.
I think its just happened to me. Host had problems with that phwhatever bb and lost server for quite a bit longer that I thought. Was during christmas so I wasn't paying to much mind to any of the details. Low and behold last weeks update...I've gone from almost 600 pages to 120... OMG!!! lol Fortunately, my high traffic pages are in place and traffic is on pace to double from last month. My initial concern was penalty, but rankings stuck across the board for all remaining pages. This is not indicative of a penalty. This leads me to conclude the server crash was responsible for the dump on this sites pages. They've actually gone up by 5 in the index since the update. I suppose I'll have a better idea next update. Another shrinkage and I acually will really panic.... Cheers
The same problem happened to a new site of one of our clients. An idiotic server admin made a change to mod rewrite config and left for Christmas. The site was down for several days and get wiped completely in Google, down to zero from 250 already indexed pages. Hopefully, the recovery confirms your observation about not being penalised for downtime. After 10 days from the accident, some 50 pages are back in the index and the SERPS for the recovered pages are similar what they used to be.