Dinnerbone recently revealed that work on 1.8.1 - mostly centered around optimizations and bugfixes - is well underway. While work on 1.9 may be in progress, no significant details are known about it at this time. Dinnerbone further added that the recent lack of Snapshots was perfectly normal, as every major update to Minecraft has generally seen a break between the update release, and the next round of Snapshot tests. He added that Snapshots had not slowed for any other significant reason, and rumors to the contrary were unfounded.
As for what 1.9 may hold in the future, who knows? At this time, there are no salient details about the future update, other than it being something planned for the future.
Searge humorously suggested that the new version be named 1.10, to make a point about iterative program versions. In programming, version numbers do not generally follow "addition/subtraction"-style logic (ie. "version 1.8, 1.9, 2.0"), but increasing numbers depending on major, minor, and other revisions. In its current form, Minecraft version numbers would incrementally increase from 1.8 to 1.9, then 1.10, 1.11, and so on.