Misha Dmitriev and the team have announced the JFluid/NetBeans Profiler Milestone 2 release. It (still) requires a modified VM and does not yet integrate with NetBeans 4.0 beta, but does CPU and memory profiling like never before! Better thread-aware profiling is the biggest enhancement to this release. Other details here.
Note there’s also profiling in Sun’s Java Studio Enterprise 7 (currently in EA) with integrated load generation, HTTP monitoring and method-level instrumentation and profiling.