A small commercial building that fronts on North Boyle but is addressed as 4260 Westminster Place in the Central West End / Gaslight Square neighborhood is now undergoing a $40,000 rehab by owner Jeffrey Raglani. Based on the permit information, the building may be converted to a residential unit.
In May 2010, the building was proposed for demolition under the previous owner, but that demolition was denied by the city’s Preservation Board. More information is available on the Preservation Research Office blog.
Hat tip goes to Jeff Vines (of STL-STyLe fame) for spotting the rehab work getting underway.
Below is a Google Streetview capture of the building, whose brick has begun to spall.

Jeff Vines has also provided a snapshot of a rendering posted on the building.

Click here for a map of the area.
Thanks, Jeff!
A two-family home located at 6023-25 Kingsbury in Skinker-DeBaliviere is under a $150,000 rehab by Manor Real Estate Residential, LLC.
Below is a recent photograph of the building (at center):

A single family home located at 2831 Lafayette in the Gate District will be rehabbed at a cost of $150,000 by owner “Lafayette and Oregon Townhomes, LLC”.
Below is a Geo St. Louis photograph of the building:

West End City Apartments is managed by Detroit-based Village Green and includes hundreds of apartments inside the historic Westmoreland, Senate, and Congress buildings near the intersection of Union and Pershing. If plans go accordingly, another brand new, 82-unit building will be added to their portfolio.
Below is a photograph of a rendering found inside the West End City Apartments Leasing Office. According to the leasing agent, the development is nearly financed and a groundbreaking is being planned soon. No specific date or time frame for construction is available, however.

An STLToday.com article from September 2011 (presumed still current) has more details.
Paramount Property Development has been issued a $1.2 million building permit to rehab an old warehouse at 2200 Locust into a residential building with commercial on the ground floor. A planned unit total was not available.
Below is a Google Streetview capture of the building:

A $1 million development at the corner of Tower Grove and Chouteau in Forest Park Southeast (AKA the Grove) will bring six new rental townhomes to the neighborhood.
Washington University Medical Center Redevelopment Corp. (WUMCRC) reported the news yesterday on its blog.
Below is a drawing of an elevation of one of the buildings, courtesy of WUMCRC.

The developer is Above All Development, a newcomer.
The Gotham development, a multi-million dollar development east of the most developed portion of the Delmar Loop, includes a rehab of a 66-unit former hotel at 5900 Enright and a new mixed use building, shown below, at 5901 Delmar.
The new building is progressing nicely, adding a sense of urban scale to this portion of Delmar (again).
Click here for a map of the area.
Click here for the earlier STLNABEDEV story on the Gotham Development.
A new single family home at 1728 Carroll in the Lafayette Square neighborhood is nearly completed.
The home is a bookend to a small development of single family homes on the south side of the 1700 block of Carroll. As of right now, only one other home is completed (1702 Carroll, at the opposite end of the block), but some of the remaining lots on the block have been sold and await construction.
Below is a recent photo of 1728 Carroll:

The CORTEX development, in its second phase, will add to its ranks a rehabbed Southwestern Bell building at 4240 Duncan, to be called the Heritage Building. The recently issued building permit to turn the old warehouse-style building into lab space was valued at $23.5 million. (As an aside, CORTEX also has planned a new MetroLink station near Boyle Avenue, just adjacent to the Heritage Building).
For more information on CORTEX’s Phase Two development in the eastern portion of the Central West End, including plans for MetroLink, see this January 2012 nextSTL article.
Below is a rendering of a rehabbed Heritage Building:

The former commercial building at 4432-34 Olive in the Central West End is nearing the end of its $450,000 rehab.
Below is a recent photograph of the building:

And below is a shot of the building prior to rehab (Google Streetview):
