Apologies if this is the wrong place, this is my first post here.
I've found a bug in the RSS import module in WordPress 2.8.4. It seems to trigger on particularly long items in the RSS feed that's being imported. When it occurs, everything up to the long item is imported successfully, but the long item and everything after it is not.
I've not tested extensively to see what the length is that triggers the bug, but the one item that triggered it for me was 152 kB of post text (so probably 155-156 kB when the wrapping XML is included).
Luckily the feed I'm importing only has one such item, so I just copy-pasted it into a new page manually, then ran the following items through the RSS importer again. Still, figured it might be worth mentioning!