The VC is the nearest major cluster of galaxies and, as such, it is an ideal place to study various types of galaxies and their interactions. The distance, estimated at 15 to 20 Mpc, implies that fairly faint objects can be reached with modest telescopes and observing time, at least for surface photometry purposes. Additionally, the nearness of the VC to the Milky Way implies that individual studies of galaxies in other spectral bands, e.g., HI or Far Infrared (FIR), can be very detailed. The obvious shortcoming is the large angular extent of the cluster; to cover its core region as well as its Southern Extension one needs to study ~ 300 square degrees of the sky.
Because of the fortunate accident of our nearness to the VC, the population of dwarf galaxies, objects with M > -18 mag, is a particularly attractive subject of study. Dwarf galaxies, and in particular the star-forming irregulars, have been thought to represent a local population that is most similar to the distant, first generation galaxies in the early Universe. The reason is that, observationally, these objects are devoid of large-scale patterns such as spiral arms thus the traditional star-formation triggers are probably not active. In addition, many dwarf irregulars have been found to have low metal abundances with the record being 1/52 solar for I Zw 18.
The landmark work dealing with the general population of the VC is undoubtedly the Las Campanas survey of galaxies (VCC catalog: Binggeli et al. 1985). The wide scale of the photographic plates used at the 2.5-m telescope allowed fairly confident morphological classification of more than 2000 objects. Among the dwarf galaxy (DG) population, Binggeli et al. identified approximately 1000 such objects that are considered cluster members; 90% of these are dwarf ellipticals (dE) and the remaining 10% are classified as either dwarf irregulars (dI) or blue compact dwarfs (BCD). The VC membership assignment by Binggeli et al. was based on morphology; this was checked later using redshifts (e.g., Drinkwater et al. 1996) and was found to be mostly correct.
A second landmark contribution to the study of the VC was by Hoffman et al. (1987, 1989), in the Arecibo survey of all late-type galaxies in the VCC catalog. Although at times missing flux, because of the single beam observations, the HI survey is important because it (a) allowed the elimination of some late-type dwarfs from the list of VC members, by finding that these were background objects, and (b) yielding the total HI content and an indication about the dynamics of the HI from the line profile. Parenthetically, in most of the cases of dI and BCD galaxies the profiles measured at Arecibo were far from typical of disks; no two-horned profiles were observed for bona-fide members of these classes arguing against a disk explanation for these galaxies.
The third landmark contribution allowed the evaluation of the influence of hot intra-cluster gas (ICM) to the galaxy evolution. The major contribution came from the ROSAT survey of the VC (Böhringer et al. 1994) with some contribution from the EUVE observations (Berghöfer et al. 2000) where lower temperature gas was targeted. The latest EUV maps indicate that this kind of emission is relegated to the immediate neighborhood of M87 and requires the presence there of relativistic electrons. In the context of a hot ICM, I want to mention the ASCA "mystery hot spot" showed at this meeting by Hans Böhringer, where a region ~ 4 square degrees wide, somewhat to the South-West of M49, shows much higher temperatures than any region in the VC: 4.5 keV vs. a typical cluster temperature of 2.5 keV (see also Shibata et al. 2001). This is suggested by Kikuchi et al. (2000) to be the result of infall of the M49 group toward M87 with ~ 1000 km/sec, causing a shock in the ISM.